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A023429
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Generalized Catalan Numbers.
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0
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1, 1, 1, 1, 1, 1, 1, 2, 4, 7, 11, 17, 27, 44, 73, 122, 204, 340, 566, 945, 1586, 2674, 4521, 7656, 12982, 22047, 37509, 63934, 109166, 186685, 319679, 548091, 940819, 1616830, 2781706, 4790949, 8259748, 14253480, 24618561, 42557378
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,8
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MAPLE
| a:= proc(n) option remember;
`if` (n=0, 1, a(n-1) +add (a(k)*a(n-4-k), k=3..n-4))
end:
seq (a(n), n=0..50); # Alois P. Heinz, May 07, 2011
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MATHEMATICA
| Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ n-4-k ], {k, 3, n-4} ];
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CROSSREFS
| Cf. A000108, A001006, A004148, A006318.
Sequence in context: A006999 A005252 A023430 * A023428 A093911 A152398
Adjacent sequences: A023426 A023427 A023428 * A023430 A023431 A023432
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KEYWORD
| nonn,easy
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AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
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