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A107863 Column 1 of triangle A107862; a(n) = C( n*(n+1)/2 + n, n). 1
1, 2, 10, 84, 1001, 15504, 296010, 6724520, 177232627, 5317936260, 179013799328, 6681687099710, 273897571557780, 12233149001721760, 591315394579074378, 30756373941461374800, 1712879663609111933495, 101696990867999141755140 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..17.

FORMULA

a(n) = [x^(n*(n+1)/2)] 1/(1 - x)^(n+1). - Ilya Gutkovskiy, Oct 10 2017

PROG

(PARI) a(n)=binomial(n*(n+1)/2+n, n)

CROSSREFS

Cf. A107862, A014068.

Sequence in context: A113332 A321398 A180715 * A065866 A322406 A302935

Adjacent sequences:  A107860 A107861 A107862 * A107864 A107865 A107866

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 04 2005

STATUS

approved

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Last modified May 23 11:05 EDT 2019. Contains 323513 sequences. (Running on oeis4.)