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Expansion of Product_{k>=0} (1+x^(4*k+1))^3.
3

%I #4 Aug 28 2015 03:15:34

%S 1,3,3,1,0,3,9,9,3,3,12,18,12,6,18,37,33,15,22,54,66,42,36,81,114,84,

%T 57,112,189,171,109,156,279,294,201,222,405,486,360,328,564,747,617,

%U 504,783,1123,1017,783,1065,1602,1605

%N Expansion of Product_{k>=0} (1+x^(4*k+1))^3.

%F a(n) ~ exp(Pi*sqrt(n)/2) / (2^(5/4) * n^(3/4)).

%t nmax=50; CoefficientList[Series[Product[(1+x^(4*k+1))^3, {k, 0, nmax}], {x, 0, nmax}], x]

%Y Cf. A261612, A261615, A261633, A169975, A261630.

%K nonn

%O 0,2

%A _Vaclav Kotesovec_, Aug 27 2015