A367637 G.f. A(x) satisfies A(x) = 1 / (1 - x * A(x^6)).

1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 9, 12, 16, 21, 27, 34, 43, 55, 71, 92, 119, 153, 196, 251, 322, 414, 533, 686, 882, 1133, 1455, 1869, 2402, 3088, 3970, 5103, 6558, 8427, 10829, 13917, 17888, 22992, 29551, 37979, 48809, 62727, 80617, 103612, 133167

Offset: 0

Author

Seiichi Manyama, Dec 01 2023

Keywords

• nonn

Comments

This sequence is different from A005708.

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..5000

Crossrefs

Cf. A000621, A367794, A367800.

Cf. A005708, A101916.

Programs

PARI

a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, (i-1)\6, v[j+1]*v[i-6*j])); v;

Formula

a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/6)} a(k) * a(n-1-6*k).