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A023423 Generalized Catalan Numbers. 1
1, 1, 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 128, 257, 517, 1042, 2104, 4256, 8624, 17504, 35585, 72455, 147746, 301706, 616948, 1263240, 2589840, 5316033, 10924681, 22475831, 46290195 (list; graph; refs; listen; history; internal format)
OFFSET

0,8

MATHEMATICA

Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ n-2-k ], {k, 5, n-2} ];

CROSSREFS

Cf. A000108, A004148, A004149.

Sixth row of A064645.

Sequence in context: A103662 A180211 A186026 * A180210 A079838 A109912

Adjacent sequences:  A023420 A023421 A023422 * A023424 A023425 A023426

KEYWORD

nonn,easy

AUTHOR

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

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Last modified February 15 10:06 EST 2012. Contains 205763 sequences.