A320235 G.f.: Product_{k>=1, j>=1} (1 + x^(k*j))^2.

1, 2, 5, 12, 24, 48, 94, 172, 310, 550, 946, 1602, 2679, 4394, 7123, 11424, 18082, 28344, 44039, 67754, 103412, 156660, 235489, 351602, 521650, 768998, 1127100, 1642946, 2381929, 3436028, 4932998, 7049004, 10028422, 14207122, 20044327, 28169528, 39439899

Offset

0,2

Comments

Self-convolution of A107742.

Links

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

Formula

Conjecture: log(a(n)) ~ Pi*sqrt(n*log(n)/3).

Mathematica

nmax = 50; CoefficientList[Series[Product[(1+x^(k*j))^2, {k, 1, nmax}, {j, 1, Floor[nmax/k] + 1}], {x, 0, nmax}], x]

Crossrefs

Cf. A107742, A280451, A320236.

Sequence in context: A261369 A116714 A023615 * A034483 A267004 A322779

Adjacent sequences: A320232 A320233 A320234 * A320236 A320237 A320238

Keyword

nonn

Author

Vaclav Kotesovec, Oct 08 2018

Status

approved