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A034768 Dirichlet convolution of Catalan numbers with themselves. 0
1, 2, 4, 11, 28, 88, 264, 868, 2864, 9752, 33592, 117676, 416024, 1486064, 5348936, 19390573, 70715340, 259292608, 955277400, 3534536244, 13128241368, 48932567632, 182965127280, 686119347008, 2579808294844, 9723893218928 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..26.

FORMULA

a(n) ~ 2^(2*n-1) / (sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Sep 11 2019

MATHEMATICA

Table[Sum[CatalanNumber[n/d - 1]*CatalanNumber[d - 1], {d, Divisors[n]}], {n, 1, 25}] (* Vaclav Kotesovec, Sep 10 2019 *)

CROSSREFS

Sequence in context: A148134 A151425 A148135 * A148136 A148137 A148138

Adjacent sequences:  A034765 A034766 A034767 * A034769 A034770 A034771

KEYWORD

nonn

AUTHOR

Erich Friedman

STATUS

approved

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Last modified September 27 21:12 EDT 2021. Contains 347698 sequences. (Running on oeis4.)