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A023433
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Generalized Catalan Numbers.
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0
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1, 1, 1, 1, 1, 2, 4, 7, 12, 21, 38, 70, 129, 238, 442, 827, 1556, 2939, 5570, 10593, 20214, 38690, 74251, 142844, 275430, 532215, 1030440, 1998733, 3883552, 7557865, 14730670, 28751455, 56192036, 109959882, 215431019, 422541192
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,6
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MAPLE
| a:= proc(n) option remember;
`if` (n=0, 1, a(n-1) +add (a(k)*a(n-3-k), k=2..n-3))
end:
seq (a(n), n=0..50); # Alois P. Heinz, May 08, 2011
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MATHEMATICA
| Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ n-3-k ], {k, 2, n-3} ];
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CROSSREFS
| Cf. A000108, A001006, A004148, A006318.
Sequence in context: A103197 A000709 A054161 * A190168 A005126 A054151
Adjacent sequences: A023430 A023431 A023432 * A023434 A023435 A023436
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KEYWORD
| nonn,easy
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AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
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