Catalan numbers/Pascal's triangle: Difference between revisions
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1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845
</pre>
=={{header|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|4.2.8}}
{| class="wikitable"
! 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
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'''PASLIN''' ''( n -- [ 1..(n,p)..1 ] ) ''
get previous line
add a zero at tail
duplicate it, rotate right coeffs and sum
'''CATLN''' ''( n -- C(n) )''
get Pascal_line(2n)
return line[n+1]-line[n]
|}
{{in}}
<pre>
≪ { } 1 15 FOR j CATLN j + NEXT ≫ EVAL
</pre>
{{out}}
<pre>
1: { 1 2 5 14 42 132 429 1430 4862 16796 58786 208012 742900 2674440 9694845 }
</pre>
Runs in 119 seconds on a HP-28S.
=={{header|Ruby}}==
<syntaxhighlight lang="tcl">def catalan(num)
Line 1,997 ⟶ 2,040:
[1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845]
</pre>
=={{header|Run BASIC}}==
<syntaxhighlight lang="runbasic">n = 15
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