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A329805
Expansion of Product_{i>=1, j>=1} (1 + x^(i*j) + x^(2*i*j)).
0
1, 1, 3, 4, 10, 14, 27, 39, 71, 101, 170, 242, 390, 551, 852, 1198, 1803, 2512, 3687, 5101, 7351, 10088, 14289, 19472, 27208, 36810, 50790, 68262, 93200, 124453, 168279, 223364, 299473, 395214, 525754, 690103, 911644, 1190447, 1562449, 2030381, 2649162, 3426591
OFFSET
0,3
FORMULA
G.f.: Product_{k>=1} ((1 - x^(3*k)) / (1 - x^k))^A000005(k).
MATHEMATICA
nmax = 41; CoefficientList[Series[Product[((1 - x^(3 k))/(1 - x^k))^DivisorSigma[0, k], {k, 1, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 21 2019
STATUS
approved