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A265975 Expansion of Product_{k>=1} 1/(1 - 4*k*x^k). 4
1, 4, 24, 108, 512, 2164, 9464, 39004, 163008, 663588, 2713752, 10954764, 44328512, 178160724, 716821752, 2874497660, 11532111232, 46187508676, 185028540696, 740595436652, 2964628293504, 11862432443764, 47467812675320, 189902835709212, 759756868215872 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000

FORMULA

a(n) ~ c * 4^n, where c = Product_{m>=2} 1/(1 - m/4^(m-1)) = 2.700170514502619666262858845683166558216386190684736249639219328278569...

MAPLE

b:= proc(n, i) option remember; `if`(n=0 or i=1,

      4^n, b(n, i-1) +i*4*b(n-i, min(n-i, i)))

    end:

a:= n-> b(n$2):

seq(a(n), n=0..32);  # Alois P. Heinz, Aug 23 2019

MATHEMATICA

nmax=40; CoefficientList[Series[Product[1/(1-4*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

CROSSREFS

Cf. A006906, A265951, A265974, A265976.

Cf. A246935, A246936.

Sequence in context: A166036 A120908 A145655 * A306610 A059153 A129032

Adjacent sequences:  A265972 A265973 A265974 * A265976 A265977 A265978

KEYWORD

nonn

AUTHOR

Vaclav Kotesovec, Dec 19 2015

STATUS

approved

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Last modified September 21 07:28 EDT 2021. Contains 347596 sequences. (Running on oeis4.)