A339985 G.f.: g(x)^2 * g(x^2), where g(x) is the g.f. of A000081.

0, 0, 0, 0, 1, 2, 6, 14, 37, 90, 232, 584, 1512, 3906, 10246, 26984, 71766, 191852, 516400, 1396760, 3797435, 10367628, 28420466, 78183462, 215791426, 597368222, 1658233794, 4614679792, 12872125836, 35982713314, 100787606966, 282832173830, 795070060983

Offset: 0

Author

Vaclav Kotesovec, Dec 25 2020

Keywords

• nonn

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..2000

Crossrefs

Cf. A000081, A217781, A339984.

Programs

Mathematica

max = 30; A000081 = Rest[Cases[ Import["https://oeis.org/A000081/b000081.txt", "Table"], {, }][[All, 2]]]; g81 = Sum[A000081[[k]]*x^k, {k, 1, max}]; g81x2 = Sum[A000081[[k]]*x^(2*k), {k, 1, max}]; CoefficientList[Series[g81^2 * g81x2, {x, 0, max}], x]

Formula

a(n) ~ 2 * A339986 * A051491^n / n^(3/2).