# Catalan numbers/Pascal's triangle

Catalan numbers/Pascal's triangle
You are encouraged to solve this task according to the task description, using any language you may know.

Print out the first   15   Catalan numbers by extracting them from Pascal's triangle.

See

## 11l

Translation of: Python
```V n = 15
V t = [0] * (n + 2)
t[1] = 1
L(i) 1 .. n
L(j) (i .< 1).step(-1)
t[j] += t[j - 1]
t[i + 1] = t[i]
L(j) (i + 1 .< 1).step(-1)
t[j] += t[j - 1]
print(t[i + 1] - t[i], end' ‘ ’)```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## 360 Assembly

For maximum compatibility, this program uses only the basic instruction set.

```CATALAN  CSECT
USING  CATALAN,R13,R12
SAVEAREA B      STM-SAVEAREA(R15)
DC     17F'0'
DC     CL8'CATALAN'
STM      STM    R14,R12,12(R13)
ST     R13,4(R15)
ST     R15,8(R13)
LR     R13,R15
LA     R12,4095(R13)
LA     R12,1(R12)
*        ----   CODE
LA     R0,1
ST     R0,T            t(1)=1
LA     R4,0            ix:i=1
LA     R6,1            by 1
LH     R7,N            to n
LOOPI    BXH    R4,R6,ENDLOOPI  loop i
LR     R5,R4           ix:j=i+1
LA     R5,2(R5)        i+2
LA     R8,0
BCTR   R8,0            by -1
LA     R9,1            to 2
LOOP1J   BXLE   R5,R8,ENLOOP1J  loop j
LR     R10,R5          j
BCTR   R10,0
SLA    R10,2
L      R2,T(R10)       r2=t(j)
LR     R1,R10          j
SH     R1,=H'4'
L      R3,T(R1)        r3=t(j-1)
AR     R2,R3           r2=r2+r3
ST     R2,T(R10)       t(j)=t(j)+t(j-1)
B      LOOP1J
ENLOOP1J EQU    *
LR     R1,R4           i
BCTR   R1,0
SLA    R1,2
L      R3,T(R1)        t(i)
LA     R1,4(R1)
ST     R3,T(R1)        t(i+1)
LR     R5,R4           ix:j=i+2
LA     R5,3(R5)        i+3
LA     R8,0
BCTR   R8,0            by -1
LA     R9,1            to 2
LOOP2J   BXLE   R5,R8,ENLOOP2J  loop j
LR     R10,R5          j
BCTR   R10,0
SLA    R10,2
L      R2,T(R10)       r2=t(j)
LR     R1,R10          j
SH     R1,=H'4'
L      R3,T(R1)        r3=t(j-1)
AR     R2,R3           r2=r2+r3
ST     R2,T(R10)       t(j)=t(j)+t(j-1)
B      LOOP2J
ENLOOP2J EQU    *
LR     R1,R4           i
BCTR   R1,0
SLA    R1,2
L      R2,T(R1)        t(i)
LA     R1,4(R1)
L      R3,T(R1)        t(i+1)
SR     R3,R2
CVD    R3,P
UNPK   Z,P
MVC    C,Z
OI     C+L'C-1,X'F0'
MVC    WTOBUF(8),C+8
WTO    MF=(E,WTOMSG)
B      LOOPI
ENDLOOPI EQU    *
*        ----   END CODE
CNOP   0,4
L      R13,4(0,R13)
LM     R14,R12,12(R13)
XR     R15,R15
BR     R14
*        ----   DATA
N        DC     H'15'
T        DC     17F'0'
P        DS     PL8
Z        DS     ZL16
C        DS     CL16
WTOMSG   DS     0F
DC     H'80'
DC     H'0'
WTOBUF   DC     CL80' '
YREGS
END```
Output:
```00000001
00000002
00000005
00000014
00000042
00000132
00000429
00001430
00004862
00016796
00058786
00208012
00742900
02674440
09694845```

## Action!

```INCLUDE "D2:REAL.ACT" ;from the Action! Tool Ki

DEFINE PTR="CARD"
DEFINE REALSIZE="6"

PTR FUNC GetItemAddr(PTR buf BYTE i)
RETURN (buf+REALSIZE*i)

PROC Main()
DEFINE COUNT="15"
BYTE ARRAY buf(102) ;(COUNT+2)*REALSIZE
REAL POINTER r1,r2
REAL c
BYTE i,j

Put(125) PutE() ;clear the screen

IntToReal(1,r1)

FOR i=1 TO COUNT
DO
j=i+1
WHILE j>=2
DO
j==-1
OD
RealAssign(r1,r2) ;t(i+1)=t(i)

j=i+2
WHILE j>=2
DO
j==-1
OD
RealSub(r2,r1,c) ;c=t(i+1)-t(i)
PrintF("C(%B)=",i) PrintRE(c)
OD
RETURN```
Output:
```C(1)=1
C(2)=2
C(3)=5
C(4)=14
C(5)=42
C(6)=132
C(7)=429
C(8)=1430
C(9)=4862
C(10)=16796
C(11)=58786
C(12)=208012
C(13)=742900
C(14)=2674440
C(15)=9694845
```

Uses package Pascal from the Pascal triangle solution[[1]]

```with Ada.Text_IO, Pascal;

procedure Catalan is

Last: Positive := 15;
Row: Pascal.Row := Pascal.First_Row(2*Last+1);

begin
for I in 1 .. Last loop
Row := Pascal.Next_Row(Row);
Row := Pascal.Next_Row(Row);
end loop;
end Catalan;
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## ALGOL 68

Translation of: C++
```INT n = 15;
[ 0 : n + 1 ]INT t;
t[0] := 0;
t[1] := 1;
FOR i TO n DO
FOR j FROM i   BY -1 TO 2 DO t[j] := t[j] + t[j-1] OD;
t[i+1] := t[i];
FOR j FROM i+1 BY -1 TO 2 DO t[j] := t[j] + t[j-1] OD;
print( ( whole( t[i+1] - t[i], 0 ), " " ) )
OD```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## ALGOL W

```begin
% print the first 15 Catalan numbers from Pascal's triangle %
integer n;
n := 15;
begin
integer array pascalLine ( 1 :: n + 1 );
% the Catalan numbers are the differences between the middle and middle - 1 numbers of the odd %
% lines of Pascal's triangle (lines with 3 or more numbers)                                    %
% note - we only need to calculate the left side of the triangle                               %
pascalLine( 1 ) := 1;
for c := 2 until n + 1 do begin
% even line %
for i := c - 1 step -1 until 2 do pascalLine( i ) := pascalLine( i - 1 ) + pascalLine( i );
pascalLine( c ) := pascalLine( c - 1 );
% odd line %
for i := c     step -1 until 2 do pascalLine( i ) := pascalLine( i - 1 ) + pascalLine( i );
writeon( i_w := 1, s_w := 0, " ", pascalLine( c ) - pascalLine( c - 1 ) )
end for_c
end
end.```
Output:
``` 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## APL

```      ⍝ Based heavily on the J solution
CATALAN←{¯1↓↑-/1 ¯1↓¨(⊂⎕IO+0 0)⍉¨0 2⌽¨⊂(⎕IO-⍨⍳N){+\⍣⍺⊢⍵}⍤0 1⊢1⍴⍨N←⍵+2}
```
Output:
```      CATALAN 15
1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## Arturo

```n: 15
t: new array.of:n+2 0

t\[1]: 1

loop 1..n 'i [
loop i..1 'j -> t\[j]: t\[j] + t\[j-1]
t\[i+1]: t\[i]
loop (i+1)..1 'j -> t\[j]: t\[j] + t\[j-1]
prints t\[i+1] - t\[i]
prints " "
]
print ""
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## AutoHotkey

Works with: AutoHotkey_L
```/* Generate Catalan Numbers
//
// smgs: 20th Feb, 2014
*/
Array := [], Array[2,1] := Array[2,2] := 1 ; Array inititated and 2nd row of pascal's triangle assigned
INI := 3 ; starts with calculating the 3rd row and as such the value
Loop, 31 ; every odd row is taken for calculating catalan number as such to obtain 15 we need 2n+1
{
if ( A_index > 2 )
{
Loop, % A_INDEX
{
old := ini-1, 		index := A_index, 		index_1 := A_index + 1
Array[ini, index_1] := Array[old, index] + Array[old, index_1]
Array[ini, 1] := Array[ini, ini] := 1
line .= Array[ini, A_index] " "
}
;~ MsgBox % line ; gives rows of pascal's triangle
; calculating every odd row starting from 1st so as to obtain catalan's numbers
if ( mod(ini,2) != 0)
{
StringSplit, res, line, %A_Space%
ans := res0//2, ans_1 := ans++
result := result . res%ans_1% - res%ans% " "
}
line :=
ini++
}
}
MsgBox % result
```
Produces:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## AWK

```# syntax: GAWK -f CATALAN_NUMBERS_PASCALS_TRIANGLE.AWK
# converted from C
BEGIN {
printf("1")
for (n=2; n<=15; n++) {
num = den = 1
for (k=2; k<=n; k++) {
num *= (n + k)
den *= k
catalan = num / den
}
printf(" %d",catalan)
}
printf("\n")
exit(0)
}
```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## BASIC

### Applesoft BASIC

Translation of: MSX-BASIC
```10 HOME
20 n = 15
30 DIM t(n+2)
50 t(1) = 1
55 PRINT "The first 15 Catalan numbers are: "; CHR\$(10)
60 FOR i = 1 TO n
70   FOR j = i TO 1 STEP -1 : t(j) = t(j) + t(j-1) : NEXT j
80   t(i+1) = t(i)
90   FOR j = i+1 TO 1 STEP -1 : t(j) = t(j) + t(j-1) : NEXT j
100 PRINT i; ": "; t(i+1) - t(i)
120 NEXT i
130 END
```

### Chipmunk Basic

Translation of: MSX-BASIC
Works with: Chipmunk Basic version 3.6.4
```100 cls
110 n = 15
120 dim t(n+2)
130 t(1) = 1
140 print "The first 15 Catalan numbers are: ";chr\$(10)
150 for i = 1 to n
160   for j = i to 1 step -1 : t(j) = t(j)+t(j-1) : next j
170   t(i+1) = t(i)
180   for j = i+1 to 1 step -1 : t(j) = t(j)+t(j-1) : next j
190 print using "###";i;": ";
200 print using "#########";t(i+1)-t(i)
210 next i
220 end
```

### GW-BASIC

Works with: PC-BASIC version any
Works with: BASICA
Works with: QBasic
Works with: MSX BASIC

The GW-BASIC solution works without any changes.

### MSX Basic

Works with: MSX BASIC version any
```100 CLS
110 N = 15
120 DIM T(N+2)
130 T(1) = 1
140 PRINT "The first 15 Catalan numbers are: "; CHR\$(10)
150 FOR I = 1 TO N
160   FOR J = I TO 1 STEP -1 : T(J) = T(J) + T(J-1) : NEXT J
170   T(I+1) = T(I)
180   FOR J = I+1 TO 1 STEP -1 : T(J) = T(J) + T(J-1) : NEXT J
190 PRINT USING "###: #########";I; T(I+1) - T(I)
200 NEXT I
210 END
```
Output:
```The first 15 Catalan numbers are:

1:         1
2:         2
3:         5
4:        14
5:        42
6:       132
7:       429
8:      1430
9:      4862
10:     16796
11:     58786
12:    208012
13:    742900
14:   2674440
15:   9694845```

### QBasic

The MSX-BASIC solution works without any changes.

### XBasic

Translation of: MSX-BASIC
Works with: Windows XBasic
```PROGRAM	"Pascal's triangle"
VERSION	"0.0000"

DECLARE FUNCTION  Entry ()

FUNCTION  Entry ()
N = 15
DIM T[N+2]
T[1] = 1

PRINT "The first 15 Catalan numbers are: "; CHR\$(10)
FOR I = 1 TO N
FOR J = I TO 1 STEP -1
T[J] = T[J] + T[J-1]
NEXT J
T[I+1] = T[I]
FOR J = I+1 TO 1 STEP -1
T[J] = T[J] + T[J-1]
NEXT J
PRINT FORMAT\$("###",I); ": "; FORMAT\$("#########",(T[I+1] - T[I]))
NEXT I

END FUNCTION
END PROGRAM
```

### Yabasic

Translation of: MSX-BASIC
```n = 15
dim t(n+2)
t(1) = 1
print "The first 15 Catalan numbers are: \n"
for i = 1 to n
for j = i to 1 step -1
t(j) = t(j) + t(j-1)
next j
t(i+1) = t(i)
for j = i+1 to 1 step -1
t(j) = t(j) + t(j-1)
next j
print i using("###");
print ": ";
print t(i+1)-t(i) using ("#########")
next i
```

## Batch File

```@echo off
setlocal ENABLEDELAYEDEXPANSION
set n=15
set /A nn=n+1
for /L %%i in (0,1,%nn%) do set t.%%i=0
set t.1=1
for /L %%i in (1,1,%n%) do (
set /A ip=%%i+1
for /L %%j in (%%i,-1,1) do (
set /A jm=%%j-1
set /A t.%%j=t.%%j+t.!jm!
)
set /A t.!ip!=t.%%i
for /L %%j in (!ip!,-1,1) do (
set /A jm=%%j-1
set /A t.%%j=t.%%j+t.!jm!
)
set /A ci=t.!ip!-t.%%i
echo !ci!
)
)
pause
```
Output:
```1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845```

## C

```//This code implements the print of 15 first Catalan's Numbers
//Formula used:
//  __n__
//   | |  (n + k) / k  n>0
//   k=2

#include <stdio.h>
#include <stdlib.h>

//the number of Catalan's Numbers to be printed
const int N = 15;

int main()
{
//loop variables (in registers)
register int k, n;

//necessarily ull for reach big values
unsigned long long int num, den;

//the nmmber
int catalan;

//the first is not calculated for the formula
printf("1 ");

//iterating from 2 to 15
for (n=2; n<=N; ++n) {
//initializaing for products
num = den = 1;
//applying the formula
for (k=2; k<=n; ++k) {
num *= (n+k);
den *= k;
catalan = num /den;
}

//output
printf("%d ", catalan);
}

//the end
printf("\n");
return 0;
}
```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## C#

Translation of: C++
```int n = 15;
List<int> t = new List<int>() { 0, 1 };
for (int i = 1; i <= n; i++)
{
for (var j = i; j > 1; j--) t[j] += t[j - 1];
for (var j = i + 1; j > 1; j--) t[j] += t[j - 1];
Console.Write(((i == 1) ? "" : ", ") + (t[i + 1] - t[i]));
}
```
Produces:
```1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845
```

## C++

```// Generate Catalan Numbers
//
// Nigel Galloway: June 9th., 2012
//
#include <iostream>
int main() {
const int N = 15;
int t[N+2] = {0,1};
for(int i = 1; i<=N; i++){
for(int j = i; j>1; j--) t[j] = t[j] + t[j-1];
t[i+1] = t[i];
for(int j = i+1; j>1; j--) t[j] = t[j] + t[j-1];
std::cout << t[i+1] - t[i] << " ";
}
return 0;
}
```
Produces:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## Common Lisp

```(defun catalan (n)
"Return the n-th Catalan number"
(if (<= n 1)  1
(let ((result 2))
(dotimes (k (- n 2) result)
(setq result (* result (/ (+ n k 2) (+ k 2)))) ))))

(dotimes (n 15)
(print (catalan (1+ n))) )
```
Output:
```1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845```

## D

Translation of: C++
```void main() {
import std.stdio;

enum uint N = 15;
uint[N + 2] t;
t[1] = 1;

foreach (immutable i; 1 .. N + 1) {
foreach_reverse (immutable j; 2 .. i + 1)
t[j] += t[j - 1];
t[i + 1] = t[i];
foreach_reverse (immutable j; 2 .. i + 2)
t[j] += t[j - 1];
write(t[i + 1] - t[i], ' ');
}
}
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 `

See Pascal.

## EasyLang

Translation of: AWK
```print 1
for n = 2 to 15
num = 1
den = 1
for k = 2 to n
num *= n + k
den *= k
cat = num / den
.
print cat
.```

## EchoLisp

```(define dim 100)
(define-syntax-rule  (Tidx i j)  (+ i (* dim j)))

;; generates Catalan's triangle
;; T (i , j) = T(i-1,j) + T (i, j-1)

(define (T n)
(define i (modulo n dim))
(define j (quotient n dim))
(cond
((zero? i) 1) ;; left column = 1
((= i j) (T (Tidx (1- i) j))) ;; diagonal value = left value
(else (+ (T (Tidx (1- i) j)) (T (Tidx i (1- j)))))))

(remember 'T #(1))
```
Output:
```;; take elements on diagonal = Catalan numbers
(for ((i (in-range 0 16))) (write (T (Tidx i i))))

→ 1 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## EDSAC order code

Rather than store a triangular array, this solution stores the right-hand half of the current row and updates it in place. It uses the third method in the link, e.g. once we have the half row (70, 56, 28, 8, 1), the Catalan number 42 appears as 70 - 28.

``` [Catalan numbers from Pascal triangle, Rosetta Code website.
EDSAC program, Initial Orders 2]
..PZ  [blank tape and terminator]
T54K  [refer to working array with 'C']
T46K  [to call print subroutine with 'G N']

[Modification of library subroutine P7.
Prints non-negative integer, up to 10 digits, right-justified.
E25KTN
TFH17@S17@A43@G23@UFS43@T1FV4DAFG50@SFLDUFXFOFFFSFL4FT4DA49@
T31@A1FA43@G20@XFP1024FP610D@524D!FO46@O26@XFO46@SFL8FT4DE39@

[Main program]
PK  T200K GK
[Constants]
[0]   PD   [short constant 1]
[1]   P2F  [to inc address by 2]
[2]   T#C  [used in manufacturing EDSAC orders]
[3]   MF   [add to T order to make A order with same address]
[4]   #F   [set figures]
[5]   &F   [line feed]
[6]   @F   [carriage return]
[7]   P7D  [maximum n = 15]
[Variable]
[8]   PF   [n]
[Enter with acc = 0]
[9]   O4@                      [set teleprinter to figures]
T4#C  T2#C  T#C  A@  TC  [initialize first 3 terms to 1, 0, 0]
T8@  E58@                [set n := 0; jump to inc n and print C_n]
[Outer loop; here with n updated]
[17]   TF  A8@                  [acc := latest n]
L1F  A2@  T22@           [make and store order 'T 2n #C']
[22]   T#C                      [sets term := 0; also used to test for end of loop]
A2@                      [load 'T#C', initial value of order 31]
[Loop to convert e.g. (20, 15, 6, 1) to (35, 21, 7, 1); works left to right]
[24]   U31@  A3@  U29@  A1@  T30@  [set up orders on next line]
[29]   A#C  A#C  T#C            [replaced by manufactured orders]
A31@  A1@  S22@  E38@    [inc address in order 31, jump out if done]
A22@  E24@               [not done, loop back]
[38]   A22@  T48@               [initialize order 48]
[Loop to convert e.g. (35, 21, 7, 1) to (70, 56, 28, 8, 1); works right to left]
[40]   TF A48@  A3@  U46@  S1@  T47@  [set up orders on next line]
[46]   A#C  A#C  T#C            [replaced by manufactured orders]
A48@  S1@  T48@          [dec address in order 48]
A2@  S48@  G40@          [test for done, loop back if not]
A#C  LD  T#C             [double first term, e.g. 35 -> 70 (not done in loop)]
[Increment n and print Catalan number C_n]
[58]   TD                       [clear 0D, ensures sandwich bit = 0]
A8@  A@  U8@  TF         [inc n; set 0D := n by setting 0F := n]
A63@  GN                 [print n]
A#C  S4#C  TD  A68@  GN  [print Catalan number C_n, e.g. C_5 = 70 - 28 = 42]
O6@  O5@                 [print CR, LF]
A8@  S7@  G17@           [test for maximum n, loop back if not]
[75]   O4@  ZF                  [flush printer buffer; stop]
E9Z  PF                  [define entry point; enter with acc = 0]```
Output:
```          1          1
2          2
3          5
4         14
5         42
6        132
7        429
8       1430
9       4862
10      16796
11      58786
12     208012
13     742900
14    2674440
15    9694845
```

## Elixir

```defmodule Catalan do
def numbers(num) do
{result,_} = Enum.reduce(1..num, {[],{0,1}}, fn i,{list,t0} ->
t1 = numbers(i, t0)
t2 = numbers(i+1, Tuple.insert_at(t1, i+1, elem(t1, i)))
{[elem(t2, i+1) - elem(t2, i) | list], t2}
end)
Enum.reverse(result)
end

defp numbers(0, t), do: t
defp numbers(n, t), do: numbers(n-1, put_elem(t, n, elem(t, n-1) + elem(t, n)))
end

IO.inspect Catalan.numbers(15)
```
Output:
```[1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]
```

## Erlang

```-module(catalin).
-compile(export_all).
mul(N,D,S,S)->
N2=N*(S+S),
D2=D*S,
K = N2 div D2 ;
mul(N,D,S,L)->
N2=N*(S+L),
D2=D*L,
K = mul(N2,D2,S,L+1).

catl(Ans,16) -> Ans;
catl(D,S)->
C=mul(1,1,S,2),
catl([D|C],S+1).
main()->
Ans=catl(1,2).
```

## ERRE

```PROGRAM CATALAN

!\$DOUBLE

DIM CATALAN[50]

FUNCTION ODD(X)
ODD=FRC(X/2)<>0
END FUNCTION

PROCEDURE GETCATALAN(L)
LOCAL J,K,W
LOCAL DIM PASTRI[100]

L=L*2
PASTRI[0]=1
J=0
WHILE J<L DO
J+=1
K=INT((J+1)/2)
PASTRI[K]=PASTRI[K-1]
FOR W=K TO 1 STEP -1 DO
PASTRI[W]+=PASTRI[W-1]
END FOR
IF NOT(ODD(J)) THEN
K=INT(J/2)
CATALAN[K]=PASTRI[K]-PASTRI[K-1]
END IF
END WHILE
END PROCEDURE

BEGIN
LL=15
GETCATALAN(LL)
FOR I=1 TO LL DO
WRITE("### ####################";I;CATALAN[I])
END FOR
END PROGRAM```
Output:
```  1                    1
2                    2
3                    5
4                   14
5                   42
6                  132
7                  429
8                 1430
9                 4862
10                16796
11                58786
12               208012
13               742900
14              2674440
15              9694845
```

## F#

```let mutable nm=uint64(1)
let mutable dm=uint64(1)
let mutable a=uint64(1)

printf "1, "
for i = 2 to 15 do
nm<-uint64(1)
dm<-uint64(1)
for k = 2 to i do
nm <-uint64( uint64(nm) * (uint64(i)+uint64(k)))
dm <-uint64( uint64(dm) * uint64(k))
let a = uint64(uint64(nm)/uint64(dm))
printf "%u"a
if(i<>15) then
printf ", "
```

## Factor

```USING: arrays grouping io kernel math prettyprint sequences ;
IN: rosetta-code.catalan-pascal

: next-row ( seq -- seq' )
2 clump [ sum ] map 1 prefix 1 suffix ;

: pascal ( n -- seq )
1 - { { 1 } } swap [ dup last next-row suffix ] times ;

15 2 * pascal [ length odd? ] filter [
dup length 1 = [ 1 ]
[ dup midpoint@ dup 1 + 2array swap nths first2 - ] if
pprint bl
] each drop
```
Output:
```1 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440
```

## FreeBASIC

```' version 15-09-2015
' compile with: fbc -s console

#Define size 31                 ' (N * 2 + 1)

Sub pascal_triangle(rows As Integer, Pas_tri() As ULongInt)

Dim As Integer x, y

For x = 1 To rows
Pas_tri(1,x) = 1
Pas_tri(x,1) = 1
Next

For x = 2 To rows
For y = 2 To rows + 1 - x
Pas_tri(x, y) = pas_tri(x - 1 , y) + pas_tri(x, y - 1)
Next
Next

End Sub

' ------=< MAIN >=------

Dim As Integer count, row
Dim As ULongInt triangle(1 To size, 1 To size)

pascal_triangle(size, triangle())

'  1   1   1   1   1   1
'  1   2   3   4   5   6
'  1   3   6  10  15  21
'  1   4  10  20  35  56
'  1   5  15  35  70 126
'  1   6  21  56 126 252
' The Pascal triangle is rotated 45 deg.
' to find the Catalan number we need to follow the diagonal
' for top left to bottom right
' take the number on diagonal and subtract the number in de cell
' one up and one to right
' 1 (2 - 1), 2 (6 - 4), 5 (20 - 15) ...

Print "The first 15 Catalan numbers are" : print
count = 1 : row = 2
Do
Print Using "###: #########"; count; triangle(row, row) - triangle(row +1, row -1)
row = row + 1
count =  count + 1
Loop Until count > 15

' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End
```
Output:
```The first 15 Catalan numbers are

1:         1
2:         2
3:         5
4:        14
5:        42
6:       132
7:       429
8:      1430
9:      4862
10:     16796
11:     58786
12:    208012
13:    742900
14:   2674440
15:   9694845```

## Go

Translation of: C++
```package main

import "fmt"

func main() {
const n = 15
t := [n + 2]uint64{0, 1}
for i := 1; i <= n; i++ {
for j := i; j > 1; j-- {
t[j] += t[j-1]
}
t[i+1] = t[i]
for j := i + 1; j > 1; j-- {
t[j] += t[j-1]
}
fmt.Printf("%2d : %d\n", i, t[i+1]-t[i])
}
}
```
Output:
``` 1 : 1
2 : 2
3 : 5
4 : 14
5 : 42
6 : 132
7 : 429
8 : 1430
9 : 4862
10 : 16796
11 : 58786
12 : 208012
13 : 742900
14 : 2674440
15 : 9694845
```

## Groovy

Translation of: C
```class Catalan
{
public static void main(String[] args)
{
BigInteger N = 15;
BigInteger k,n,num,den;
BigInteger  catalan;
print(1);
for(n=2;n<=N;n++)
{
num = 1;
den = 1;
for(k=2;k<=n;k++)
{
num = num*(n+k);
den = den*k;
catalan = num/den;
}
print(" " + catalan);
}

}
}
​
```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

As required by the task this implementation extracts the Catalan numbers from Pascal's triangle, rather than calculating them directly. Also, note that it (correctly) produces [1, 1] as the first two numbers.

```import System.Environment (getArgs)

-- Pascal's triangle.
pascal :: [[Integer]]
pascal = [1] : map (\row -> 1 : zipWith (+) row (tail row) ++ [1]) pascal

-- The Catalan numbers from Pascal's triangle.  This uses a method from
-- http://www.cut-the-knot.org/arithmetic/algebra/CatalanInPascal.shtml
-- (see "Grimaldi").
catalan :: [Integer]
catalan = map (diff . uncurry drop) \$ zip [0..] (alt pascal)
where alt (x:_:zs) = x : alt zs -- every other element of an infinite list
diff (x:y:_) = x - y
diff (x:_)   = x

main :: IO ()
main = do
ns <- fmap (map read) getArgs :: IO [Int]
mapM_ (print . flip take catalan) ns
```
Output:
```./catalan 15
[1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,2674440]
```

## Icon and Unicon

The following works in both languages. It avoids computing elements in Pascal's triangle that aren't used.

```link math

procedure main(A)
limit := (integer(A[1])|15)+1
every write(right(binocoef(i := 2*seq(0)\limit,i/2)-binocoef(i,i/2+1),30))
end
```

Sample run:

```->cn
1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845
->
```

## J

```   Catalan=. }:@:(}.@:((<0 1)&|:) - }:@:((<0 1)&|:@:(2&|.)))@:(i. +/\@]^:[ #&1)@:(2&+)
```
Example use:
```   Catalan 15
1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

A structured derivation of Catalan follows:

```   o=. @: NB. Composition of verbs (functions)
( PascalTriangle=. i. ((+/\@]^:[)) #&1 ) 5
1 1  1  1  1
1 2  3  4  5
1 3  6 10 15
1 4 10 20 35
1 5 15 35 70
( MiddleDiagonal=. (<0 1)&|: )               o PascalTriangle 5
1 2 6 20 70
( AdjacentLeft=.   MiddleDiagonal o (2&|.) ) o PascalTriangle 5
1 4 15 1 5

( Catalan=. }: o (}. o MiddleDiagonal - }: o AdjacentLeft) o PascalTriangle o (2&+) f. ) 5
1 2 5 14 42

Catalan
}:@:(}.@:((<0 1)&|:) - }:@:((<0 1)&|:@:(2&|.)))@:(i. +/\@]^:[ #&1)@:(2&+)
```

## Java

Translation of: C++
```public class Test {
public static void main(String[] args) {
int N = 15;
int[] t = new int[N + 2];
t[1] = 1;

for (int i = 1; i <= N; i++) {

for (int j = i; j > 1; j--)
t[j] = t[j] + t[j - 1];

t[i + 1] = t[i];

for (int j = i + 1; j > 1; j--)
t[j] = t[j] + t[j - 1];

System.out.printf("%d ", t[i + 1] - t[i]);
}
}
}
```
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## JavaScript

### ES5

Iteration

Translation of: C++
```var n = 15;
for (var t = [0, 1], i = 1; i <= n; i++) {
for (var j = i; j > 1; j--) t[j] += t[j - 1];
t[i + 1] = t[i];
for (var j = i + 1; j > 1; j--) t[j] += t[j - 1];
document.write(i == 1 ? '' : ', ', t[i + 1] - t[i]);
}
```
Output:
```1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845
```

### ES6

Functional composition

```(() => {
'use strict';

// CATALAN

// catalanSeries :: Int -> [Int]
let catalanSeries = n => {
let alternate = xs => xs.reduce(
(a, x, i) => i % 2 === 0 ? a.concat([x]) : a, []
),
diff = xs => xs.length > 1 ? xs[0] - xs[1] : xs[0];

return alternate(pascal(n * 2))
.map((xs, i) => diff(drop(i, xs)));
}

// PASCAL

// pascal :: Int -> [[Int]]
let pascal = n => until(
m => m.level <= 1,
m => {
let nxt = zipWith(
(a, b) => a + b, [0].concat(m.row), m.row.concat(0)
);
return {
row: nxt,
triangle: m.triangle.concat([nxt]),
level: m.level - 1
}
}, {
level: n,
row: [1],
triangle: [
[1]
]
}
)
.triangle;

// GENERIC FUNCTIONS

// zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
let zipWith = (f, xs, ys) =>
xs.length === ys.length ? (
xs.map((x, i) => f(x, ys[i]))
) : undefined;

// until :: (a -> Bool) -> (a -> a) -> a -> a
let until = (p, f, x) => {
let v = x;
while (!p(v)) v = f(v);
return v;
}

// drop :: Int -> [a] -> [a]
let drop = (n, xs) => xs.slice(n);

// tail :: [a] -> [a]
let tail = xs => xs.length ? xs.slice(1) : undefined;

return tail(catalanSeries(16));
})();
```
Output:
```[1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,2674440,9694845]
```

## jq

The first identity (C(2n,n) - C(2n, n-1)) given in the reference is used in accordance with the task description, but it would of course be more efficient to factor out C(2n,n) and use the expression C(2n,n)/(n+1). See also Catalan_numbers#jq for other alternatives.

Warning: jq uses IEEE 754 64-bit arithmetic, so the algorithm used here for Catalan numbers loses precision for n > 30 and fails completely for n > 510.

```def binomial(n; k):
if k > n / 2 then binomial(n; n-k)
else reduce range(1; k+1) as \$i (1; . * (n - \$i + 1) / \$i)
end;

# Direct (naive) computation using two numbers in Pascal's triangle:
def catalan_by_pascal: . as \$n | binomial(2*\$n; \$n) - binomial(2*\$n; \$n-1);```

Example:

```(range(0;16), 30, 31, 510, 511) | [., catalan_by_pascal]
```
Output:
```\$ jq -n -c -f Catalan_numbers_Pascal.jq
[0,0]
[1,1]
[2,2]
[3,5]
[4,14]
[5,42]
[6,132]
[7,429]
[8,1430]
[9,4862]
[10,16796]
[11,58786]
[12,208012]
[13,742900]
[14,2674440]
[15,9694845]
[30,3814986502092304]
[31,14544636039226880]
[510,5.491717746183512e+302]
[511,null]
```

## Julia

Translation of: Matlab
```# v0.6

function pascal(n::Int)
r = ones(Int, n, n)
for i in 2:n, j in 2:n
r[i, j] = r[i-1, j] + r[i, j-1]
end
return r
end

function catalan_num(n::Int)
p = pascal(n + 2)
p[n+4:n+3:end-1] - diag(p, 2)
end

@show catalan_num(15)
```
Output:
`catalan_num(15) = [1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]`

## Kotlin

```// version 1.1.2

import java.math.BigInteger

val ONE = BigInteger.ONE

fun pascal(n: Int, k: Int): BigInteger {
if (n == 0 || k == 0) return ONE
val num = (k + 1..n).fold(ONE) { acc, i -> acc * BigInteger.valueOf(i.toLong()) }
val den = (2..n - k).fold(ONE) { acc, i -> acc * BigInteger.valueOf(i.toLong()) }
return num / den
}

fun catalanFromPascal(n: Int) {
for (i in 1 until n step 2) {
val mi = i / 2 + 1
val catalan = pascal(i, mi) - pascal(i, mi - 2)
println("\${"%2d".format(mi)} : \$catalan")
}
}

fun main(args: Array<String>) {
val n = 15
catalanFromPascal(n * 2)
}
```
Output:
``` 1 : 1
2 : 2
3 : 5
4 : 14
5 : 42
6 : 132
7 : 429
8 : 1430
9 : 4862
10 : 16796
11 : 58786
12 : 208012
13 : 742900
14 : 2674440
15 : 9694845
```

## Lua

For each line of odd-numbered length from Pascal's triangle, print the middle number minus the one immediately to its right. This solution is heavily based on the Lua code to generate Pascal's triangle from the page for that task.

```function nextrow (t)
local ret = {}
t[0], t[#t + 1] = 0, 0
for i = 1, #t do ret[i] = t[i - 1] + t[i] end
return ret
end

function catalans (n)
local t, middle = {1}
for i = 1, n do
middle = math.ceil(#t / 2)
io.write(t[middle] - (t[middle + 1] or 0) .. " ")
t = nextrow(nextrow(t))
end
end

catalans(15)
```
Output:
`1 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440`

## M2000 Interpreter

Translation of: FreeBasic

We have to add -1 in For x=2 to rows, because in FreeBasic when x=rows then inner loop never happen because end value for y is 1, so lower than start value 2. In M2000 this should run from 2 to 1, so we have to exclude this situation from outer loop, adding -1, and before loop we have to include en exit from sub if rows are less than 2.

We can define integer variables (16 bit), and we can use integer literals numbers using % as last char.

Inside triangle array we use decimal numbers, using @ for first literals, so all additions next produce decimals too.

We use & to pass by reference, here anarray, to sub, but because a sub can see anything in module we can change array name inside sub to same as triangle and we can remove arguments (including size).

```Module CatalanNumbers {
Def Integer count, t_row, size=31
Dim triangle(1 to size, 1 to size)

\\ call sub
pascal_triangle(size, &triangle())

Print "The first 15 Catalan numbers are"
count = 1% : t_row = 2%

Do {
Print  Format\$("{0:0:-3}:{1:0:-15}", count, triangle(t_row, t_row) - triangle(t_row +1, t_row -1))
t_row++
count++
} Until count > 15
End

Sub pascal_triangle(rows As Integer, &Pas_tri())
Local x=0%, y=0%
For x = 1 To rows
Pas_tri( 1%, x ) = 1@
Pas_tri( x, 1% ) = 1@
Next x
if rows<2 then exit sub
For x = 2 To rows-1
For y = 2 To rows + 1 - x
Pas_tri(x, y) = pas_tri(x - 1 , y) + pas_tri(x, y - 1)
Next y
Next x
End Sub
}
CatalanNumbers```
Output:
```  1:              1
2:              2
3:              5
4:             14
5:             42
6:            132
7:            429
8:           1430
9:           4862
10:          16796
11:          58786
12:         208012
13:         742900
14:        2674440
15:        9694845
```

## Maple

```catalan:=proc(n)
local i,a:=[1],C:=[1];
for i to n do
a:=[0,op(a)]+[op(a),0];
a:=[0,op(a)]+[op(a),0];
C:=[op(C),a[i+1]-a[i]];
od;
C
end:

catalan(10);
# [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796]```

## Mathematica / Wolfram Language

This builds the entire Pascal triangle that's needed and holds it in memory. Very inefficienct, but seems to be what is asked in the problem.

```nextrow[lastrow_] := Module[{output},
output = ConstantArray[1, Length[lastrow] + 1];
Do[
output[[i + 1]] = lastrow[[i]] + lastrow[[i + 1]];
, {i, 1, Length[lastrow] - 1}];
output
]
pascaltriangle[size_] := NestList[nextrow, {1}, size]
catalannumbers[length_] := Module[{output, basetriangle},
basetriangle = pascaltriangle[2 length];
list1 = basetriangle[[# *2 + 1, # + 1]] & /@ Range[length];
list2 = basetriangle[[# *2 + 1, # + 2]] & /@ Range[length];
list1 - list2
]
(* testing *)
catalannumbers[15]
```
Output:
`{1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845}`

## MATLAB / Octave

```n = 15;
p = pascal(n + 2);
p(n + 4 : n + 3 : end - 1)' - diag(p, 2)
```
Output:
```ans =
1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845```

## Maxima

```/* The Catalan triangle can be generated using genmatrix */
genmatrix(lambda([n,k],if n>=k then binomial(n+k-1,k-1)-2*binomial(n+k-2,k-2) else 0),15,15)\$

/* The Catalan numbers are in the main diagonal */
makelist(%[i,i],i,1,15);
```
Output:
```[1,1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,2674440]
```

## Nim

Translation of: Python
```const n = 15
var t = newSeq[int](n + 2)

t[1] = 1
for i in 1..n:
for j in countdown(i, 1): t[j] += t[j-1]
t[i+1] = t[i]
for j in countdown(i+1, 1): t[j] += t[j-1]
stdout.write t[i+1] - t[i], " "
stdout.write '\n'
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 `

## OCaml

```let catalan : int ref = ref 0 in
Printf.printf "%d ," 1 ;
for i = 2 to 9  do
let nm : int ref = ref 1 in
let den : int ref = ref 1 in
for k = 2 to i do
nm := (!nm)*(i+k);
den := (!den)*k;
catalan := (!nm)/(!den) ;
done;
print_int (!catalan); print_string "," ;
done;;
```
Output:
```OUTPUT:
1 ,2,5,14,42,132,429,1430,4862
```

## Oforth

```import: mapping

: pascal( n -- [] )
[ 1 ] n #[ dup [ 0 ] + [ 0 ] rot + zipWith( #+ ) ] times ;

: catalan( n -- m )
n 2 * pascal at( n 1+ ) n 1+ / ;```
Output:
```>#catalan 15 seq map .
[1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]
```

## PARI/GP

`vector(15,n,binomial(2*n,n)-binomial(2*n,n+1))`
Output:
`%1 = [1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]`

## Pascal

```Program CatalanNumbers
type
tElement = Uint64;
var
Catalan : array[0..50] of tElement;
procedure GetCatalan(L:longint);
var
PasTri : array[0..100] of tElement;
j,k: longInt;
begin
l := l*2;
PasTri[0] := 1;
j    := 0;
while (j<L) do
begin
inc(j);
k := (j+1) div 2;
PasTri[k] :=PasTri[k-1];
For k := k downto 1 do
inc(PasTri[k],PasTri[k-1]);
IF NOT(Odd(j)) then
begin
k := j div 2;
Catalan[k] :=PasTri[k]-PasTri[k-1];
end;
end;
end;

var
i,l: longint;
Begin
l := 15;
GetCatalan(L);
For i := 1 to L do
Writeln(i:3,Catalan[i]:20);
end.
```
```  1                   1
2                   2
3                   5
4                  14
5                  42
6                 132
7                 429
8                1430
9                4862
10               16796
11               58786
12              208012
13              742900
14             2674440
15             9694845

```

## Perl

Translation of: C++
```use constant N => 15;
my @t = (0, 1);
for(my \$i = 1; \$i <= N; \$i++) {
for(my \$j = \$i; \$j > 1; \$j--) { \$t[\$j] += \$t[\$j-1] }
\$t[\$i+1] = \$t[\$i];
for(my \$j = \$i+1; \$j>1; \$j--) { \$t[\$j] += \$t[\$j-1] }
print \$t[\$i+1] - \$t[\$i], " ";
}
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

After the 28th Catalan number, this overflows 64-bit integers. We could add use bigint; use Math::GMP ":constant"; to make it work, albeit not at a fast pace. However we can use a module to do it much faster:

Library: ntheory
```use ntheory qw/binomial/;
print join(" ", map { binomial( 2*\$_, \$_) / (\$_+1) } 1 .. 1000), "\n";
```

The Math::Pari module also has a binomial, but isn't as fast and overflows its stack after 3400.

## Phix

Calculates the minimum pascal triangle in minimum memory. Inspired by the comments in, but not the code of the FreeBasic example

```constant N = 15 -- accurate to 30, nan/inf for anything over 514 (gmp version is below).
sequence catalan = {},      -- (>=1 only)
p = repeat(1,N+1)
atom p1
for i=1 to N do
p1 = p[1]*2
catalan = append(catalan,p1-p[2])
for j=1 to N-i+1 do
p1 += p[j+1]
p[j] = p1
end for
--  ?p[1..N-i+1]
end for
?catalan
```
Output:
```{1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,2674440,9694845}
```

Explanatory comments to accompany the above

```-- FreeBASIC said:
--'  1   1   1   1   1   1
--'  1   2   3   4   5   6
--'  1   3   6  10  15  21
--'  1   4  10  20  35  56
--'  1   5  15  35  70 126
--'  1   6  21  56 126 252
--' The Pascal triangle is rotated 45 deg.
--' to find the Catalan number we need to follow the diagonal
--' for top left to bottom right
--' take the number on diagonal and subtract the number in de cell
--' one up and one to right
--' 1 (2 - 1), 2 (6 - 4), 5 (20 - 15) ...
--
-- The first thing that struck me was it is twice as big as it needs to be,
--  something like this would do...
--    1   1   1   1   1   1
--        2   3   4   5   6
--            6  10  15  21
--               20  35  56
--                   70 126
--                      252
-- It is more obvious from the upper square that the diagonal on that, which is
--  that same as column 1 on this, is twice the previous, which on the second
--  diagram is in column 2. Further, once we have calculated the value for column
--  one above, we can use it immediately to calculate the next catalan number and
--  do not need to store it. Lastly we can overwrite row 1 with row 2 etc in situ,
--  and the following shows what we need for subsequent rounds:
--    1   1   1   1   1
--    3   4   5   6
--   10  15  21
--   35  56
--  126  (unused)
```

### gmp version

Library: Phix/mpfr
```with javascript_semantics
include builtins\mpfr.e

function catalanB(integer n)    -- very very fast!
sequence catalan = mpz_inits(n),
p = mpz_inits(n+1,1)
mpz p1 = mpz_init(1)
if n=0 then return p1 end if
for i=1 to n do
mpz_mul_si(p1,p[1],2)
mpz_sub(catalan[i],p1,p[2])
for j=1 to n-i+1 do
mpz_set(p[j],p1)
end for
end for
return catalan[n]
end function

printf(1,"%d: %s\n",{100,shorten(mpz_get_str(catalanB(100)))})
printf(1,"%d: %s\n",{250,shorten(mpz_get_str(catalanB(250)))})
```
Output:
```100: 89651994709013149668...20837521538745909320 (57 digits)
250: 46511679596923379649...69029457769094808256 (147 digits)
```

The above is significantly faster than the equivalent(s) on Catalan_numbers, a quick comparison showing the latter getting exponentially worse (then again I memoised the slowest recursive version):

```            800 2000  4000 8000
catalanB:  0.6s 3.5s 14.5s  64s
catalan2m: 0.7s 7.0s 64.9s 644s
```

## PicoLisp

```(de bino (N K)
(let f
'((N)
(if (=0 N) 1 (apply * (range 1 N))) )
(/
(f N)
(* (f (- N K)) (f K)) ) ) )

(for N 15
(println
(-
(bino (* 2 N) N)
(bino (* 2 N) (inc N)) ) ) )
(bye)```

## PureBasic

Translation of: C
```#MAXNUM = 15
Declare catalan()

If OpenConsole("Catalan numbers")
catalan()
Input()
End 0
Else
End -1
EndIf

Procedure catalan()
Define k.i, n.i, num.d, den.d, cat.d

Print("1 ")

For n=2 To #MAXNUM
num=1 : den =1
For k=2 To n
num * (n+k)
den * k
cat = num / den
Next
Print(Str(cat)+" ")
Next
EndProcedure
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## Python

### Procedural

Translation of: C++
```>>> n = 15
>>> t = [0] * (n + 2)
>>> t[1] = 1
>>> for i in range(1, n + 1):
for j in range(i, 1, -1): t[j] += t[j - 1]
t[i + 1] = t[i]
for j in range(i + 1, 1, -1): t[j] += t[j - 1]
print(t[i+1] - t[i], end=' ')

1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
>>>
```
Works with: Python version 2.7
```def catalan_number(n):
nm = dm = 1
for k in range(2, n+1):
nm, dm = ( nm*(n+k), dm*k )
return nm/dm

print [catalan_number(n) for n in range(1, 16)]

[1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]
```

### Composition of pure functions

Note that sequence A000108 on OEIS (referenced in the task description) confirms that the first four Catalan numbers are indeed 1, 1, 2, 5 ...

Works with: Python version 3.7
```'''Catalan numbers from Pascal's triangle'''

from itertools import (islice)

# nCatalans :: Int -> [Int]
def nCatalans(n):
'''The first n Catalan numbers,
derived from Pascal's triangle.'''

# diff :: [Int] -> Int
def diff(xs):
'''Difference between the first two items in the list,
if its length is more than one.
Otherwise, the first (only) item in the list.'''
return (
xs[0] - (xs[1] if 1 < len(xs) else 0)
) if xs else None
return list(map(
compose(diff)(uncurry(drop)),
enumerate(map(fst, take(n)(
everyOther(
pascalTriangle()
)
)))
))

# pascalTriangle :: Gen [[Int]]
def pascalTriangle():
'''A non-finite stream of
Pascal's triangle rows.'''
return iterate(nextPascal)([1])

# nextPascal :: [Int] -> [Int]
def nextPascal(xs):
'''A row of Pascal's triangle
derived from a preceding row.'''
return zipWith(add)([0] + xs)(xs + [0])

# TEST ----------------------------------------------------
# main :: IO ()
def main():
'''First 16 Catalan numbers.'''

print(
nCatalans(16)
)

# GENERIC -------------------------------------------------

# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
def compose(g):
'''Right to left function composition.'''
return lambda f: lambda x: g(f(x))

# drop :: Int -> [a] -> [a]
# drop :: Int -> String -> String
def drop(n):
'''The sublist of xs beginning at
(zero-based) index n.'''
def go(xs):
if isinstance(xs, list):
return xs[n:]
else:
take(n)(xs)
return xs
return lambda xs: go(xs)

# everyOther :: Gen [a] -> Gen [a]
def everyOther(g):
'''Every other item of a generator stream.'''
while True:
yield take(1)(g)
take(1)(g)      # Consumed, not yielded.

# fst :: (a, b) -> a
def fst(tpl):
'''First component of a pair.'''
return tpl[0]

# iterate :: (a -> a) -> a -> Gen [a]
def iterate(f):
'''An infinite list of repeated applications of f to x.'''
def go(x):
v = x
while True:
yield v
v = f(v)
return lambda x: go(x)

# take :: Int -> [a] -> [a]
# take :: Int -> String -> String
def take(n):
'''The prefix of xs of length n,
or xs itself if n > length xs.'''
return lambda xs: (
xs[0:n]
if isinstance(xs, list)
else list(islice(xs, n))
)

# uncurry :: (a -> b -> c) -> ((a, b) -> c)
def uncurry(f):
'''A function over a tuple
derived from a curried function.'''
return lambda xy: f(xy[0])(
xy[1]
)

# zipWith :: (a -> b -> c) -> [a] -> [b] -> [c]
def zipWith(f):
'''A list constructed by zipping with a
custom function, rather than with the
default tuple constructor.'''
return lambda xs: lambda ys: (
list(map(f, xs, ys))
)

# MAIN ---
if __name__ == '__main__':
main()
```
Output:
`[1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]`

## Quackery

```  [ [] 0 rot 0 join
witheach
[ tuck +
rot join swap ]
drop ]                is nextline ( [ --> [ )

[ ' [ 1 ] swap times
[ nextline nextline
dup dup size 2 /
split nip
2 split drop
do - echo sp ]
drop ]                is catalan  ( n -->   )

15 catalan```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## Racket

```#lang racket

(define (next-half-row r)
(define r1 (for/list ([x r] [y (cdr r)]) (+ x y)))
`(,(* 2 (car r1)) ,@(for/list ([x r1] [y (cdr r1)]) (+ x y)) 1 0))

(let loop ([n 15] [r '(1 0)])
(cons (- (car r) (cadr r))
(if (zero? n) '() (loop (sub1 n) (next-half-row r)))))
;; -> '(1 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900
;;      2674440 9694845)
```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2015.12
```constant @pascal = [1], -> @p { [0, |@p Z+ |@p, 0] } ... *;

constant @catalan = gather for 2, 4 ... * -> \$ix {
my @row := @pascal[\$ix];
my \$mid = +@row div 2;
take [-] @row[\$mid, \$mid+1]
}

.say for @catalan[^20];
```
Output:
```1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845
35357670
129644790
477638700
1767263190
6564120420```

## REXX

### explicit subscripts

All of the REXX program examples can handle arbitrary large numbers.

```/*REXX program  obtains and displays  Catalan numbers  from  a  Pascal's triangle.      */
parse arg N .                                    /*Obtain the optional argument from CL.*/
if N=='' | N==","  then N=15                     /*Not specified?  Then use the default.*/
numeric digits max(9, N%2 + N%8)                 /*so we can handle huge Catalan numbers*/
@.=0;   @.1=1                                    /*stem array default; define 1st value.*/

do i=1  for N;                               ip=i+1
do j=i   by -1  for N;   jm=j-1;   @.j=@.j+@.jm;    end /*j*/
@.ip=@.i;           do k=ip  by -1  for N;   km=k-1;   @.k=@.k+@.km;    end /*k*/
say  @.ip - @.i                                /*display the   Ith   Catalan number.  */
end   /*i*/                                    /*stick a fork in it,  we're all done. */
```

output   when using the default input:

```1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845
```

### implicit subscripts

```/*REXX program  obtains and displays  Catalan numbers  from  a  Pascal's triangle.      */
parse arg N .                                    /*Obtain the optional argument from CL.*/
if N=='' | N==","  then N=15                     /*Not specified?  Then use the default.*/
numeric digits max(9, N%2 + N%8)                 /*so we can handle huge Catalan numbers*/
@.=0;  @.1=1                                     /*stem array default; define 1st value.*/
do i=1  for N;  ip=i+1
do j=i   by -1  for N;  @.j=@.j+@(j-1);   end  /*j*/
@.ip=@.i;              do k=ip  by -1  for N;  @.k=@.k+@(k-1);   end  /*k*/
say  @.ip - @.i                   /*display the   Ith   Catalan number.  */
end   /*i*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
@:  parse arg !;   return @.!                    /*return the value of   @.[arg(1)]     */
```

output   is the same as the 1st version.

### using binomial coefficients

```/*REXX program  obtains and displays  Catalan numbers  from  a  Pascal's triangle.      */
parse arg N .                                    /*Obtain the optional argument from CL.*/
if N=='' | N==","  then N=15                     /*Not specified?  Then use the default.*/
numeric digits max(9, N%2 + N%8)                 /*so we can handle huge Catalan numbers*/
do j=1  for N              /* [↓]  display   N   Catalan numbers. */
say  comb(j+j, j) % (j+1)  /*display the   Jth   Catalan number.  */
end   /*j*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
!:    procedure; parse arg z;   _=1;     do j=1  for arg(1);  _=_*j;  end;        return _
/*──────────────────────────────────────────────────────────────────────────────────────*/
comb: procedure; parse arg x,y;        if x=y  then return 1;   if y>x  then return 0
if x-y<y  then y=x-y;     _=1;   do j=x-y+1  to x;  _=_*j;  end;       return _/!(y)
```

output   is the same as the 1st version.

### binomial coefficients, memoized

This REXX version uses memoization for the calculation of factorials.

```/*REXX program  obtains and displays  Catalan numbers  from  a  Pascal's triangle.      */
parse arg N .                                    /*Obtain the optional argument from CL.*/
if N=='' | N==","  then N=15                     /*Not specified?  Then use the default.*/
numeric digits max(9, N%2 + N%8)                 /*so we can handle huge Catalan numbers*/
!.=.
do j=1  for N              /* [↓]  display   N   Catalan numbers. */
say  comb(j+j, j) % (j+1)  /*display the   Jth   Catalan number.  */
end   /*j*/
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
!:    procedure expose !.;  parse arg z;     if !.z\==. then return !.z;  _=1
do j=1  for arg(1);   _=_*j;   end;        !.z=_;   return _
/*──────────────────────────────────────────────────────────────────────────────────────*/
comb: procedure expose !.;  parse arg x,y;   if x=y  then return 1;  if y>x  then return 0
if x-y<y  then y=x-y;     _=1;   do j=x-y+1  to x;  _=_*j;  end;       return _/!(y)
```

output   is the same as the 1st version.

## Ring

```n=15
cat = list(n+2)
cat[1]=1
for i=1 to n
for j=i+1 to 2 step -1
cat[j]=cat[j]+cat[j-1]
next
cat[i+1]=cat[i]
for j=i+2 to 2 step -1
cat[j]=cat[j]+cat[j-1]
next
see "" + (cat[i+1]-cat[i]) + " "
next```

Output:

```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## RPL

We have taken the opportunity provided by the task to develop a routine that recursively computes Pascal's triangle. If the challenge was to look for high Catalan numbers, memoizing the triangle would make sense.

Works with: Halcyon Calc version 4.2.8
RPL code Comment
```≪ IF THEN LAST 1 + → n1
≪ n1 2 - PASLIN
{ } n1 + RDM
DUP ARRY→ DROP n1 ROLLD n1 →ARRY +
≫ ELSE [ 1 ] END
≫ ‘PASLIN’ STO

≪
DUP DUP + PASLIN
SWAP GETI ROT ROT GET SWAP -
≫ ‘CATLN’ STO
```
```PASLIN ( n -- [ 1..(n,p)..1 ] )
get previous line
duplicate it, rotate right coeffs and sum

CATLN ( n -- C(n) )
get Pascal_line(2n)
return line[n+1]-line[n]

```
Input:
```≪ { } 1 15 FOR j CATLN j + NEXT ≫ EVAL
```
Output:
```1: { 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 }
```

Runs in 119 seconds on an HP-28S.

### Fast, idiomatic approach

Using the built-in `COMB` function, which returns coefficients of Pascal's triangle:

```≪ { } 1 15 FOR j
j DUP + j COMB LAST 1 - COMB - + NEXT
≫ EVAL
```

Same output than above, runs in 2.4 seconds on an HP-28S.

## Ruby

```def catalan(num)
t = [0, 1] #grows as needed
(1..num).map do |i|
i.downto(1){|j| t[j] += t[j-1]}
t[i+1] = t[i]
(i+1).downto(1) {|j| t[j] += t[j-1]}
t[i+1] - t[i]
end
end

p catalan(15)
```
Output:
```[1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]
```

## Run BASIC

```n = 15
dim t(n+2)
t(1) = 1
for i = 1 to n
for  j = i to 1 step -1  : t(j) = t(j) + t(j-1): next j
t(i+1) = t(i)
for  j = i+1 to 1 step -1: t(j) = t(j) + t(j-1 : next j
print t(i+1) - t(i);" ";
next i```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 `

## Rust

```fn main()
{let n=15usize;
let mut t= [0; 17];
t[1]=1;
let mut j:usize;
for i in 1..n+1
{
j=i;
loop{
if j==1{
break;
}
t[j]=t[j] + t[j-1];
j=j-1;
}
t[i+1]= t[i];
j=i+1;
loop{
if j==1{
break;
}
t[j]=t[j] + t[j-1];
j=j-1;
}
print!("{} ", t[i+1]-t[i]);
}
}
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 `

## Scala

```def catalan(n: Int): Int =
if (n <= 1) 1
else (0 until n).map(i => catalan(i) * catalan(n - i - 1)).sum

(1 to 15).map(catalan(_))
```
Output:

See it in running in your browser by Scastie (JVM).

## Scilab

```n=15
t=zeros(1,n+2)
t(1)=1
for i=1:n
for j=i+1:-1:2
t(j)=t(j)+t(j-1)
end
t(i+1)=t(i)
for j=i+2:-1:2
t(j)=t(j)+t(j-1)
end
disp(t(i+1)-t(i))
end
```
Output:
```    1.
2.
5.
14.
42.
132.
429.
1430.
4862.
16796.
58786.
208012.
742900.
2674440.
9694845.  ```

## Seed7

```\$ include "seed7_05.s7i";

const proc: main is func
local
const integer: N is 15;
var array integer: t is [] (1) & N times 0;
var integer: i is 0;
var integer: j is 0;
begin
for i range 1 to N do
for j range i downto 2 do
t[j] +:= t[j - 1];
end for;
t[i + 1] := t[i];
for j range i + 1 downto 2 do
t[j] +:= t[j - 1];
end for;
write(t[i + 1] - t[i] <& " ");
end for;
writeln;
end func;```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## Sidef

Translation of: Ruby
```func catalan(num) {
var t = [0, 1]
(1..num).map { |i|
flip(^i    ).each {|j| t[j+1] += t[j] }
t[i+1] = t[i]
flip(^i.inc).each {|j| t[j+1] += t[j] }
t[i+1] - t[i]
}
}

say catalan(15).join(' ')
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## smart BASIC

```PRINT "Catalan Numbers from Pascal's Triangle"!PRINT
x = 15
DIM t(x+2)
t(1) = 1
FOR n = 1 TO x
FOR  m = n TO 1 STEP -1
t(m) = t(m) + t(m-1)
NEXT m
t(n+1) = t(n)
FOR  m = n+1 TO 1 STEP -1
t(m) = t(m) + t(m-1)
NEXT m
PRINT n,"#######":t(n+1) - t(n)
NEXT n
```

## Tcl

```proc catalan n {
set result {}
array set t {0 0 1 1}
for {set i 1} {[set k \$i] <= \$n} {incr i} {
for {set j \$i} {\$j > 1} {} {incr t(\$j) \$t([incr j -1])}
set t([incr k]) \$t(\$i)
for {set j \$k} {\$j > 1} {} {incr t(\$j) \$t([incr j -1])}
lappend result [expr {\$t(\$k) - \$t(\$i)}]
}
return \$result
}

puts [catalan 15]
```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845`

## TI-83 BASIC

```"CATALAN
15→N
seq(0,I,1,N+2)→L1
1→L1(1)
For(I,1,N)
For(J,I+1,2,-1)
L1(J)+L1(J-1)→L1(J)
End
L1(I)→L1(I+1)
For(J,I+2,2,-1)
L1(J)+L1(J-1)→L1(J)
End
Disp L1(I+1)-L1(I)
End```
Output:
```               1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845
Done ```

## Vala

Translation of: C++
```void main() {
const int N = 15;
uint64[] t = {0, 1};
for (int i = 1; i <= N; i++) {
for (int j = i; j > 1; j--) t[j] = t[j] + t[j - 1];
t[i + 1] = t[i];
for (int j = i + 1; j > 1; j--) t[j] = t[j] + t[j - 1];
print(@"\$(t[i + 1] - t[i]) ");
}
print("\n");
}
```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## VBScript

To run in console mode with cscript.

```dim t()
if Wscript.arguments.count=1 then
n=Wscript.arguments.item(0)
else
n=15
end if
redim t(n+1)
't(*)=0
t(1)=1
for i=1 to n
ip=i+1
for j = i to 1 step -1
t(j)=t(j)+t(j-1)
next 'j
t(i+1)=t(i)
for j = i+1 to 1 step -1
t(j)=t(j)+t(j-1)
next 'j
Wscript.echo t(i+1)-t(i)
next 'i
```

## Visual Basic

Translation of: Rexx
Works with: Visual Basic version VB6 Standard
```Sub catalan()
Const n = 15
Dim t(n + 2) As Long
Dim i  As Integer, j As Integer
t(1) = 1
For i = 1 To n
For j = i + 1 To 2 Step -1
t(j) = t(j) + t(j - 1)
Next j
t(i + 1) = t(i)
For j = i + 2 To 2 Step -1
t(j) = t(j) + t(j - 1)
Next j
Debug.Print i, t(i + 1) - t(i)
Next i
End Sub 'catalan
```
Output:
``` 1
2
5
14
42
132
429
1430
4862
16796
58786
208012
742900
2674440
9694845
```

## Wren

Translation of: C++
```var n = 15
var t = List.filled(n+2, 0)
t[1] = 1
for (i in 1..n) {
if (i > 1) for (j in i..2) t[j] = t[j] + t[j-1]
t[i+1] = t[i]
if (i > 0) for (j in i+1..2) t[j] = t[j] + t[j-1]
System.write("%(t[i+1]-t[i]) ")
}
System.print()
```
Output:
```1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
```

## XPL0

Translation of: C++
```def N = 15;
int T(N+2), I, J;
[T(0):= 0;  T(1):= 1;
for I:= 1 to N do
[for J:= I downto 2 do T(J):= T(J) + T(J-1);
T(I+1):= T(I);
for J:= I+1 downto 2 do T(J):= T(J) + T(J-1);
IntOut(0, T(I+1) - T(I));  ChOut(0, ^ );
];
]```
Output:
`1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 `

## Zig

Uses comptime functionality to compile Pascal's triangle into the object code, then at runtime, it's simply a table lookup. (uses code from AKS primality task.)

```const std = @import("std");

pub fn main() !void {
const stdout = std.io.getStdOut().writer();

var n: u32 = 1;
while (n <= 15) : (n += 1) {
const row = binomial(n * 2).?;
try stdout.print("{d:2}  {d:8}\n", .{ n, row[n] - row[n + 1] });
}
}

pub fn binomial(n: u32) ?[]const u64 {
if (n >= rmax)
return null
else {
const k = n * (n + 1) / 2;
return pascal[k .. k + n + 1];
}
}

const rmax = 68;

// evaluated and created at compile-time
const pascal = build: {
@setEvalBranchQuota(100_000);
var coefficients: [(rmax * (rmax + 1)) / 2]u64 = undefined;
coefficients[0] = 1;
var j: u32 = 0;
var k: u32 = 1;
var n: u32 = 1;
while (n < rmax) : (n += 1) {
var prev = coefficients[j .. j + n];
var next = coefficients[k .. k + n + 1];
next[0] = 1;
var i: u32 = 1;
while (i < n) : (i += 1)
next[i] = prev[i] + prev[i - 1];
next[i] = 1;
j = k;
k += n + 1;
}
break :build coefficients;
};
```
Output:
``` 1         1
2         2
3         5
4        14
5        42
6       132
7       429
8      1430
9      4862
10     16796
11     58786
12    208012
13    742900
14   2674440
15   9694845
```

## zkl

Translation of: PARI/GP

using binomial coefficients.

```fcn binomial(n,k){ (1).reduce(k,fcn(p,i,n){ p*(n-i+1)/i },1,n) }
(1).pump(15,List,fcn(n){ binomial(2*n,n)-binomial(2*n,n+1) })```
Output:
```L(1,2,5,14,42,132,429,1430,4862,16796,58786,208012,742900,2674440,9694845)
```

## ZX Spectrum Basic

Translation of: C++
```10 LET N=15
20 DIM t(N+2)
30 LET t(2)=1
40 FOR i=2 TO N+1
50 FOR j=i TO 2 STEP -1: LET t(j)=t(j)+t(j-1): NEXT j
60 LET t(i+1)=t(i)
70 FOR j=i+1 TO 2 STEP -1: LET t(j)=t(j)+t(j-1): NEXT j
80 PRINT t(i+1)-t(i);" ";
90 NEXT i
```