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A129763 Sum[ Binomial[ n+k-1, n ]^2, {k,1,n} ] / n. +0
1
1, 5, 39, 369, 3898, 44239, 528083, 6544745, 83496720, 1090091650, 14501708246, 195954553755, 2682953977174, 37150480629539, 519455719162283, 7325383709872345, 104080732316126716, 1488685017986884528 (list; graph; listen)
OFFSET

1,2

COMMENT

Note that Sum[ Binomial[ n+k-1, n ], {k,1,n} ] / n = Catalan(n) = A000108(n).

FORMULA

a(n) = Sum[ Binomial[ n+k-1, n ]^2, {k,1,n} ] / n.

MATHEMATICA

Table[ Sum[ Binomial[ n+k-1, n ]^2, {k, 1, n} ] / n, {n, 1, 30} ]

CROSSREFS

Cf. A000108 = Catalan numbers.

Sequence in context: A135849 A105426 A115187 this_sequence A070767 A124549 A024216

Adjacent sequences: A129760 A129761 A129762 this_sequence A129764 A129765 A129766

KEYWORD

nonn

AUTHOR

Alexander Adamchuk (alex(AT)kolmogorov.com), May 15 2007

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Last modified December 1 19:22 EST 2009. Contains 167811 sequences.


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