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A320238
G.f.: Product_{k>=1, j>=1} (1 + x^(k*j)) / (1 - x^(k*j))^2.
3
1, 3, 11, 31, 85, 209, 504, 1138, 2514, 5339, 11098, 22432, 44535, 86523, 165496, 311187, 577190, 1055524, 1907423, 3405574, 6016826, 10520065, 18222215, 31275320, 53230224, 89860112, 150551503, 250388180, 413572707, 678574627, 1106396434, 1793009335
OFFSET
0,2
COMMENTS
Convolution of A107742 and A320236.
LINKS
FORMULA
Conjecture: log(a(n)) ~ Pi * sqrt(5*n*log(n)/6).
MATHEMATICA
nmax = 50; CoefficientList[Series[Product[(1+x^(k*j))/(1-x^(k*j))^2, {k, 1, nmax}, {j, 1, Floor[nmax/k] + 1}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Oct 08 2018
STATUS
approved