



0, 0, 0, 1, 2, 4, 7, 13, 24, 48, 99, 221, 512, 1268, 3247, 8773, 24400, 70896, 211347, 653541, 2068472, 6755684, 22541135, 77305981, 270435640, 969413776, 3539893923, 13212871629, 50180362320, 194412817844, 765590169935, 3070433223317
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OFFSET

0,5


LINKS

Table of n, a(n) for n=0..31.


FORMULA

G.f. satisfies: A(x) = x^3*((2+x)/(1+x) + (1+x)*A'(x))/(2+3*x+2*x^2). a(n+3) = (1)^n*Sum_{k=0..n} Sum{j=0..[k/2]} (kj)!/(k2*j)! for n>=0. a(n+3) = a(n+2) + (1)^n*A072374(n) for n>=1.


PROG

(PARI) a(n)=if(n<3, 0, (1)^(n3)*sum(k=0, n3, sum(j=0, k\2, (kj)!/(k2*j)!)))


CROSSREFS

Cf. A113287, A113288, A113290, A072374.
Sequence in context: A005255 A086445 A127602 * A102112 A102113 A034440
Adjacent sequences: A113288 A113289 A113290 * A113292 A113293 A113294


KEYWORD

sign


AUTHOR

Paul D. Hanna, Oct 23 2005


STATUS

approved



