This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A261649 Expansion of Product_{k>=0} ((1+x^(3*k+1))/(1-x^(3*k+1)))^2. 3
 1, 4, 8, 12, 20, 36, 56, 80, 120, 180, 252, 348, 492, 680, 912, 1228, 1652, 2180, 2856, 3744, 4860, 6256, 8044, 10284, 13048, 16520, 20848, 26140, 32672, 40756, 50596, 62576, 77256, 95060, 116540, 142592, 174036, 211736, 257056, 311448, 376332, 453764, 546160 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(n) ~ exp(Pi*sqrt(2*n/3)) * Gamma(1/3)^2 / (2^(7/4) * 3^(5/12) * Pi^(4/3) * n^(7/12)). MATHEMATICA nmax=60; CoefficientList[Series[Product[((1+x^(3*k+1))/(1-x^(3*k+1)))^2, {k, 0, nmax}], {x, 0, nmax}], x] CROSSREFS Cf. A015128, A156616, A080054, A007096, A261610, A261651. Sequence in context: A322958 A123723 A279227 * A298797 A311664 A190891 Adjacent sequences:  A261646 A261647 A261648 * A261650 A261651 A261652 KEYWORD nonn AUTHOR Vaclav Kotesovec, Aug 28 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)