A360888 - OEIS

A360888

G.f. satisfies A(x) = 1 + x * (1 + x^2)^2 * A(x * (1 + x^2)).

1, 1, 1, 3, 6, 11, 29, 71, 179, 505, 1405, 4128, 12639, 39268, 127059, 420281, 1423787, 4955200, 17579398, 63796635, 236161396, 890544028, 3422553065, 13377869976, 53184706291, 214870633711, 881485304157, 3671033616614, 15507956547021, 66429816610908

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

LINKS

Table of n, a(n) for n=0..29.

FORMULA

a(0) = 1; a(n) = Sum_{k=0..floor(n-1)/2} binomial(n+1-2*k,k) * a(n-1-2*k).

PROG

(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, (i-1)\2, binomial(i+1-2*j, j)*v[i-2*j])); v;

CROSSREFS

Cf. A360887, A360889.

Cf. A360885.