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A339985
G.f.: g(x)^2 * g(x^2), where g(x) is the g.f. of A000081.
3
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
0,6
LINKS
FORMULA
a(n) ~ 2 * A339986 * A051491^n / n^(3/2).
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]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 25 2020
STATUS
approved