Magic constant

Magic constant is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

A magic square is a square grid containing consecutive integers from 1 to N², arranged so that every row, column and diagonal adds up to the same number. That number is a constant. There is no way to create a valid N x N magic square that does not sum to the associated constant.

EG

A 3 x 3 magic square always sums to 15.

    ┌───┬───┬───┐
    │ 2 │ 7 │ 6 │
    ├───┼───┼───┤
    │ 9 │ 5 │ 1 │
    ├───┼───┼───┤
    │ 4 │ 3 │ 8 │
    └───┴───┴───┘

A 4 x 4 magic square always sums to 34.

Traditionally, the sequence leaves off terms for n = 0 and n = 1 as the magic squares of order 0 and 1 are trivial; and a term for n = 2 because it is impossible to form a magic square of order 2.

Task

• Starting at order 3, show the first 20 magic constants.
• Show the 1000th magic constant. (Order 1003)
• Find and show the order of the smallest N x N magic square whose constant is greater than 10¹ through 10¹⁰.

Stretch

• Find and show the order of the smallest N x N magic square whose constant is greater than 10¹¹ through 10²⁰.

See also

• Wikipedia: Magic constant
• OEIS: A006003 (Similar sequence, though it includes terms for 0, 1 & 2.)

Basic

QB64

<lang qbasic>$NOPREFIX

DIM order AS INTEGER DIM target AS INTEGER64

PRINT "First 20 magic constants:" FOR i = 3 TO 22

   PRINT USING "####,  "; MagicSum(i);
   IF i MOD 5 = 2 THEN PRINT

NEXT i PRINT PRINT USING "1000th magic constant: ##########,"; MagicSum(1002) PRINT PRINT "Smallest order magic square with a constant greater than:" FOR i = 1 TO 13

   target = 10 ^ i
   DO
       order = order + 1
   LOOP UNTIL MagicSum(order) > target
   PRINT USING "10^**: #####,"; i; order
   order = order * 2 - 1

NEXT i

FUNCTION MagicSum&& (n AS INTEGER)

   MagicSum&& = (n * n + 1) / 2 * n

END FUNCTION</lang>

Output:

First 20 magic constants:
   15     34     65    111    175
  260    369    505    671    870
1,105  1,379  1,695  2,056  2,465
2,925  3,439  4,010  4,641  5,335

1000th magic constant: 503,006,505

Smallest order magic square with a constant greater than:
10^*1:      3
10^*2:      6
10^*3:     13
10^*4:     28
10^*5:     59
10^*6:    126
10^*7:    272
10^*8:    585
10^*9:  1,260
10^10:  2,715
10^11:  5,849
10^12: 12,600
10^13: 27,145

Factor

Works with: Factor version 0.99 2021-06-02

<lang factor>USING: formatting io kernel lists lists.lazy math math.functions math.ranges prettyprint sequences tools.memory.private ;

magic-constants ( -- list )

   3 lfrom [ dup sq 1 + 2 / * ] lmap-lazy ;

smallest ( m -- n )

   [ magic-constants 3 lfrom lzip ] dip
   '[ first _ 10^ > ] lfilter car second ;

"First 20 magic constants:" print 20 magic-constants ltake [ pprint bl ] leach nl nl "1000th magic constant:" print 999 magic-constants lnth commas print nl "Smallest order magic square with a constant greater than:" print 20 [1,b] [ dup smallest commas "10^%02d: %s\n" printf ] each </lang>

Output:

First 20 magic constants:
15 34 65 111 175 260 369 505 671 870 1105 1379 1695 2056 2465 2925 3439 4010 4641 5335 

1000th magic constant:
503,006,505

Smallest order magic square with a constant greater than:
10^01: 3
10^02: 6
10^03: 13
10^04: 28
10^05: 59
10^06: 126
10^07: 272
10^08: 585
10^09: 1,260
10^10: 2,715
10^11: 5,849
10^12: 12,600
10^13: 27,145
10^14: 58,481
10^15: 125,993
10^16: 271,442
10^17: 584,804
10^18: 1,259,922
10^19: 2,714,418
10^20: 5,848,036

Raku

<lang perl6>use Lingua::EN::Numbers:ver<2.8+>;

my @magic-constants = lazy (3..∞).hyper.map: { (1 + .²) * $_ / 2 };

put "First 20 magic constants: ", @magic-constants[^20]»., say "1000th magic constant: ", @magic-constants[999]., say "\nSmallest order magic square with a constant greater than:";

(1..20).map: -> $p {printf "10%-2s: %s\n", $p.&super, comma 3 + @magic-constants.first( * > exp($p, 10), :k ) }</lang>

Output:

First 20 magic constants: 15 34 65 111 175 260 369 505 671 870 1,105 1,379 1,695 2,056 2,465 2,925 3,439 4,010 4,641 5,335
1000th magic constant: 503,006,505

Smallest order magic square with a constant greater than:
10¹ : 3
10² : 6
10³ : 13
10⁴ : 28
10⁵ : 59
10⁶ : 126
10⁷ : 272
10⁸ : 585
10⁹ : 1,260
10¹⁰: 2,715
10¹¹: 5,849
10¹²: 12,600
10¹³: 27,145
10¹⁴: 58,481
10¹⁵: 125,993
10¹⁶: 271,442
10¹⁷: 584,804
10¹⁸: 1,259,922
10¹⁹: 2,714,418
10²⁰: 5,848,036

Wren

Library: Wren-seq

Library: Wren-fmt

Library: Wren-big

<lang ecmascript>import "./seq" for Lst import "./fmt" for Fmt import "./big" for BigInt

var magicConstant = Fn.new { |n| (n*n + 1) * n / 2 }

var ss = ["\u2070", "\u00b9", "\u00b2", "\u00b3", "\u2074",

         "\u2075", "\u2076", "\u2077", "\u2078", "\u2079"]

var superscript = Fn.new { |n| (n < 10) ? ss[n] : (n < 20) ? ss[1] + ss[n - 10] : ss[2] + ss[0] }

System.print("First 20 magic constants:") var mc20 = (3..22).map { |n| magicConstant.call(n) }.toList for (chunk in Lst.chunks(mc20, 10)) Fmt.print("$5d", chunk)

Fmt.print("\n1,000th magic constant: $,d", magicConstant.call(1002))

System.print("\nSmallest order magic square with a constant greater than:") var count = 1 var n = BigInt.three var power = BigInt.ten while (count <= 20) {

   if (magicConstant.call(n) > power) {
       Fmt.print("10$-2s : $,9i", superscript.call(count), n)
       power = power * 10
       count = count + 1
   }
   n = n.inc

}</lang>

Output:

First 20 magic constants:
   15    34    65   111   175   260   369   505   671   870
 1105  1379  1695  2056  2465  2925  3439  4010  4641  5335

1,000th magic constant: 503,006,505

Smallest order magic square with a constant greater than:
10¹  :         3
10²  :         6
10³  :        13
10⁴  :        28
10⁵  :        59
10⁶  :       126
10⁷  :       272
10⁸  :       585
10⁹  :     1,260
10¹⁰ :     2,715
10¹¹ :     5,849
10¹² :    12,600
10¹³ :    27,145
10¹⁴ :    58,481
10¹⁵ :   125,993
10¹⁶ :   271,442
10¹⁷ :   584,804
10¹⁸ : 1,259,922
10¹⁹ : 2,714,418
10²⁰ : 5,848,036