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!)
 A261566 Expansion of Product_{k>=1} (1/(1 + 2*x^k))^k. 4
 1, -2, 0, -6, 16, -18, 48, -94, 208, -426, 752, -1646, 3360, -6578, 13056, -26358, 53456, -105890, 211392, -424366, 850544, -1699290, 3393136, -6795646, 13601184, -27188130, 54358000, -108752870, 217552976, -435033618, 869999584, -1740145118, 3480497584 (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 * (-2)^n, where c = Product_{j>=1} 1/(1 - 1/(-2)^j)^(j+1) = 0.81033497534928929188778847125052151513524786804782471307090750707405... MATHEMATICA nmax = 40; CoefficientList[Series[Product[(1/(1 + 2*x^k))^k, {k, 1, nmax}], {x, 0, nmax}], x] nmax = 40; CoefficientList[Series[Exp[Sum[(-1)^k*2^k/k*x^k/(1-x^k)^2, {k, 1, nmax}]], {x, 0, nmax}], x] CROSSREFS Cf. A071109, A255528, A261567. Sequence in context: A110667 A129877 A307581 * A247443 A171734 A278746 Adjacent sequences:  A261563 A261564 A261565 * A261567 A261568 A261569 KEYWORD sign AUTHOR Vaclav Kotesovec, Aug 24 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 8 08:49 EST 2019. Contains 329862 sequences. (Running on oeis4.)