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 A023430 Generalized Catalan Numbers. 1
 1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 7, 11, 17, 27, 44, 72, 118, 194, 320, 528, 871, 1439, 2385, 3965, 6605, 11017, 18399, 30771, 51538, 86440, 145165, 244085, 410890, 692442, 1168114, 1972470, 3333834, 5639888, 9549311, 16181931, 27442827, 46575013 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,9 LINKS MAPLE A023430 := proc(n)     option remember;     if n = 0 then         1;     else         procname(n-1)+add(procname(k)*procname(n-4-k), k=4..n-4) ;     end if; end proc: # R. J. Mathar, May 01 2015 MATHEMATICA Clear[ a ]; a[ 0 ]=1; a[ n_Integer ] := a[ n ]=a[ n-1 ]+Sum[ a[ k ]*a[ n-4-k ], {k, 4, n-4} ]; CROSSREFS Cf. A000108, A001006, A004148, A006318. Sequence in context: A289010 A006999 A005252 * A023429 A023428 A093911 Adjacent sequences:  A023427 A023428 A023429 * A023431 A023432 A023433 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Sean A. Irvine, Jun 04 2019 STATUS approved

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Last modified September 29 11:42 EDT 2020. Contains 337431 sequences. (Running on oeis4.)