A188478 Binomial variation of the Catalan numbers: a(n) = sum( binomial(n-1-i, i)*a(i)*a(n-1-i), i=0..(n-1) ) with a(0)=1.

1, 1, 1, 2, 4, 11, 33, 116, 456, 1999, 9623, 50603, 288287, 1769352, 11636669, 81652911, 608857325, 4807873069, 40080193414, 351751992542, 3241754135966, 31301851579056, 316012152140592, 3329322705562603, 36539984716325869, 417102552119591395, 4944630222121834001, 60791493200390178470

Offset

0,4

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Mathematica

a[0] = 1; a[n_] := a[n] = Sum[ Binomial[n - i - 1, i] a[i]*a[n - 1 - i], {i, 0, n - 1}]; Table[a[i], {i, 0, 30}]

Crossrefs

A000108, A001147, A188479

Sequence in context: A268320 A127782 A002846 * A373922 A302547 A123444

Adjacent sequences: A188475 A188476 A188477 * A188479 A188480 A188481

Keyword

nonn,easy

Author

Olivier Gérard, Apr 01 2011

Status

approved