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A023423 Generalized Catalan Numbers. 5
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; text; internal format)
OFFSET

0,8

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..3028

MAPLE

A023423 := proc(n)

    option remember;

    if n <= 6 then

        1;

    else

        procname(n-1)+add(procname(k)*procname(n-2-k), k=5..n-2) ;

    end if;

end proc: # R. J. Mathar, Oct 10 2014

MATHEMATICA

a[0]=1; a[n_]:= a[n]=a[n-1] + Sum[a[k]*a[n-2-k], {k, 5, n-2}]; Table[a[n], {n, 0, 30}] (* modified by G. C. Greubel, Jan 01 2018 *)

PROG

(PARI) {a(n) = if(n==0, 1, a(n-1) + sum(k=5, n-2, a(k)*a(n-k-2)))};

for(n=0, 30, print1(a(n), ", ")) \\ G. C. Greubel, Jan 01 2018

CROSSREFS

Cf. A000108, A001006, A004148, A004149, A023421, A023422.

Sixth row of A064645.

Sequence in context: A275075 A275063 A186026 * A210544 A180210 A274861

Adjacent sequences:  A023420 A023421 A023422 * A023424 A023425 A023426

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified January 18 20:19 EST 2018. Contains 297865 sequences.