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A279227
Expansion of Product_{k>=1} (1 + x^(k^2))^2/(1 - x^(k^2))^2.
4
1, 4, 8, 12, 20, 36, 56, 76, 104, 152, 216, 284, 364, 484, 648, 828, 1028, 1300, 1664, 2076, 2532, 3108, 3848, 4700, 5640, 6776, 8200, 9848, 11660, 13796, 16424, 19452, 22776, 26612, 31240, 36572, 42440, 49092, 56968, 66044, 76040, 87236, 100280, 115244
OFFSET
0,2
LINKS
FORMULA
a(n) ~ (4-sqrt(2)) * Zeta(3/2) * exp(3 * Pi^(1/3) * ((4-sqrt(2)) * Zeta(3/2))^(2/3) * n^(1/3) / 2^(4/3)) / (32 * sqrt(3) * Pi^2 * n^(3/2)). - Vaclav Kotesovec, Dec 29 2016
MATHEMATICA
nmax = 100; CoefficientList[Series[Product[(1 + x^(k^2))^2/(1 - x^(k^2))^2, {k, 1, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 08 2016
STATUS
approved