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A265955 Expansion of Product_{k>=1} (1 + 2*k*x^k)/(1 - 2*k*x^k). 3
1, 4, 16, 60, 192, 596, 1776, 5020, 13760, 36916, 96336, 246316, 619392, 1530548, 3729392, 8976364, 21337920, 50195268, 116977232, 270114764, 618712640, 1406843940, 3176387120, 7126185948, 15894370816, 35253947940, 77796242768, 170868178332, 373606888128 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..3280

FORMULA

a(n) ~ c * n * 2^n, where c = 2 * Product_{m>=3} (1 + 2/(2^(m-1)/m - 1)) = 193.4198278838721371054040810054045645734538119720773785523616944906739...

MATHEMATICA

nmax=40; CoefficientList[Series[Product[(1+2*k*x^k)/(1-2*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

CROSSREFS

Cf. A006906, A022629, A032302, A032309, A070933, A265951.

Sequence in context: A032094 A282083 A261563 * A217374 A055295 A121254

Adjacent sequences:  A265952 A265953 A265954 * A265956 A265957 A265958

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Dec 19 2015

STATUS

approved

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Last modified October 27 13:45 EDT 2021. Contains 348276 sequences. (Running on oeis4.)