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A023422 Generalized Catalan Numbers. +0
2
1, 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 129, 261, 530, 1080, 2208, 4528, 9313, 19207, 39714, 82314, 170996, 355976, 742545, 1551817, 3248823, 6812947, 14309557, 30099645, 63402315 (list; graph; listen)
OFFSET

0,7

MATHEMATICA

Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ n-2-k ], {k, 4, n-2} ];

CROSSREFS

Cf. A000108, A004148, A004149.

Fifth row of A064645.

Sequence in context: A109912 A079845 A117302 this_sequence A084638 A157021 A006211

Adjacent sequences: A023419 A023420 A023421 this_sequence A023423 A023424 A023425

KEYWORD

nonn,easy

AUTHOR

Olivier Gerard (olivier.gerard(AT)gmail.com)

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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