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A264685 Expansion of Product_{k>=1} (1 + x^k)/(1 - 2*x^k). 4

%I #7 Nov 21 2015 06:19:05

%S 1,3,9,24,60,141,324,717,1560,3330,7020,14622,30225,61998,126522,

%T 257007,520326,1050396,2116116,4255584,8547330,17149350,34382295,

%U 68889840,137969466,276220962,552865365,1106356314,2213644548,4428657402,8859340926,17721640698

%N Expansion of Product_{k>=1} (1 + x^k)/(1 - 2*x^k).

%H Vaclav Kotesovec, <a href="/A264685/b264685.txt">Table of n, a(n) for n = 0..1000</a>

%F a(n) ~ c * 2^n, where c = A079555 / A048651 = Product_{k>=1} (2^k+1)/(2^k-1) = 8.25598793577825006554414084943227312652...

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

%Y Cf. A000009, A006951, A070933, A261584, A264686.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Nov 21 2015

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)