A374628 Expansion of Product_{k>=0} (1 + x^(3^k))^3.

1, 3, 3, 4, 9, 9, 6, 9, 9, 7, 12, 12, 13, 27, 27, 18, 27, 27, 15, 18, 18, 15, 27, 27, 18, 27, 27, 16, 21, 21, 19, 36, 36, 24, 36, 36, 25, 39, 39, 40, 81, 81, 54, 81, 81, 45, 54, 54, 45, 81, 81, 54, 81, 81, 42, 45, 45, 33, 54, 54, 36, 54, 54, 33, 45, 45, 42, 81, 81, 54, 81, 81, 45, 54, 54, 45, 81, 81, 54, 81, 81

Offset

0,2

Links

Table of n, a(n) for n=0..80.

Formula

G.f. A(x) satisfies A(x) = (1 + x)^3 * A(x^3).

Prog

(PARI) my(N=90, x='x+O('x^N)); Vec(prod(k=0, logint(N, 3), 1+x^3^k)^3)

Crossrefs

Cf. A039966, A120880.

Sequence in context: A183501 A086239 A016605 * A185395 A060372 A128036

Adjacent sequences: A374625 A374626 A374627 * A374629 A374630 A374631

Keyword

nonn

Author

Seiichi Manyama, Jul 14 2024

Status

approved