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A270924 Coefficient of x^n in Product_{k>=1} ((1 + x^k) / (1 - x^k))^(k*n). 7
1, 2, 16, 128, 1056, 8952, 77200, 673948, 5937792, 52689170, 470210016, 4215834328, 37945215552, 342650763392, 3102866408560, 28166168335128, 256220106742272, 2335126111557564, 21317113277158336, 194890649121580880, 1784158030393621056, 16353089279998330456 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..500

FORMULA

a(n) ~ c * d^n / sqrt(n), where d = 9.38812912875337022533876219516002188057967... and c = 0.2845468763296311652189248055322905919858...

MATHEMATICA

Table[SeriesCoefficient[Product[((1+x^k)/(1-x^k))^(k*n), {k, 1, n}], {x, 0, n}], {n, 0, 25}]

CROSSREFS

Cf. A255672, A270922, A270919, A270923.

Sequence in context: A022027 A322297 A013730 * A214623 A161737 A171451

Adjacent sequences:  A270921 A270922 A270923 * A270925 A270926 A270927

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Mar 26 2016

STATUS

approved

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Last modified October 17 04:09 EDT 2019. Contains 328106 sequences. (Running on oeis4.)