A367652 G.f. A(x) satisfies A(x) = 1 / (1 - x * (1 + x + x^2) * A(x^3)).

1, 1, 2, 4, 8, 16, 32, 65, 131, 264, 534, 1078, 2176, 4396, 8877, 17925, 36202, 73108, 147636, 298152, 602108, 1215933, 2455552, 4958915, 10014374, 20223760, 40841302, 82477816, 166561622, 336366426, 679282324, 1371791274, 2770293218, 5594527784, 11297988864

Offset

0,3

Links

Table of n, a(n) for n=0..34.

Formula

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

Crossrefs

Cf. A127680, A367653, A367654.

Cf. A367659.

Sequence in context: A264701 A195904 A101333 * A023421 A098051 A329053

Adjacent sequences: A367649 A367650 A367651 * A367653 A367654 A367655

Keyword

nonn

Author

Seiichi Manyama, Nov 26 2023

Status

approved