A255834 G.f.: Product_{k>=1} (1+x^k)^(2*k+1).
1, 3, 8, 23, 55, 129, 291, 627, 1317, 2697, 5398, 10589, 20421, 38743, 72452, 133724, 243792, 439496, 784070, 1385195, 2424971, 4209094, 7247141, 12383496, 21008559, 35398548, 59259781, 98595110, 163077878, 268221706, 438791204, 714142139, 1156552537
Offset: 0
Keywords
Links
- Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
Programs
-
Mathematica
nmax=50; CoefficientList[Series[Product[(1+x^k)^(2*k+1),{k,1,nmax}],{x,0,nmax}],x]
Formula
a(n) ~ Zeta(3)^(1/6) * exp(-Pi^4 / (2592*Zeta(3)) + Pi^2 * n^(1/3) / (12*(3*Zeta(3))^(1/3)) + 3^(4/3)/2*Zeta(3)^(1/3) * n^(2/3)) / (2^(7/6)* 3^(1/3) * sqrt(Pi) * n^(2/3)), where Zeta(3) = A002117.