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A320236 G.f.: Product_{k>=1, j>=1} 1/(1 - x^(k*j))^2. 5
1, 2, 7, 16, 41, 86, 193, 384, 787, 1504, 2899, 5338, 9852, 17586, 31330, 54490, 94350, 160370, 271171, 451776, 748460, 1225106, 1993860, 3212378, 5146851, 8175114, 12915747, 20252564, 31595134, 48964310, 75515995, 115777684, 176696336, 268231986, 405436258 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Self-convolution of A006171.

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000

FORMULA

Conjecture: log(a(n)) ~ Pi * sqrt(2*n*log(n)/3).

MATHEMATICA

nmax = 50; CoefficientList[Series[Product[1/(1-x^(k*j))^2, {k, 1, nmax}, {j, 1, Floor[nmax/k] + 1}], {x, 0, nmax}], x]

CROSSREFS

Cf. A006171, A004101, A320235.

Sequence in context: A093971 A065497 A131727 * A073371 A113224 A178945

Adjacent sequences:  A320233 A320234 A320235 * A320237 A320238 A320239

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Oct 08 2018

STATUS

approved

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Last modified December 8 04:31 EST 2019. Contains 329850 sequences. (Running on oeis4.)