A360891 G.f. satisfies A(x) = 1 + x/(1 - x^4) * A(x/(1 - x^4)).

1, 1, 1, 1, 1, 2, 4, 7, 11, 17, 32, 66, 132, 247, 463, 937, 2001, 4248, 8758, 18166, 39181, 87096, 193493, 425468, 942610, 2137196, 4930702, 11393809, 26280211, 61089849, 144157779, 343855549, 822430473, 1970839418, 4757600242, 11605042346, 28516751351

Offset

0,6

Links

Table of n, a(n) for n=0..36.

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} binomial(n-1-3*k,k) * a(n-1-4*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)\4, binomial(i-1-3*j, j)*v[i-4*j])); v;

Crossrefs

Cf. A000110, A172383, A360890.

Cf. A360899.

Sequence in context: A216116 A357926 A129929 * A073738 A137631 A003403

Adjacent sequences: A360888 A360889 A360890 * A360892 A360893 A360894

Keyword

nonn

Author

Seiichi Manyama, Feb 25 2023

Status

approved