This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A280088 Expansion of Product_{k>=1} 1/(1 - x^k)^(k!!). 2
 1, 1, 3, 6, 17, 38, 112, 280, 882, 2416, 8253, 24458, 91051, 289704, 1172288, 3980034, 17413820, 62706119, 294608079, 1118820630, 5603910081, 22328924231, 118432939871, 492897768426, 2752203529333, 11918139966134, 69709167028426, 313080284080648, 1910245872252972, 8873669214476627, 56283324138424814, 269790676411694902 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Euler transform of the double factorials (A006882). LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..300 M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version] M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures] N. J. A. Sloane, Transforms FORMULA G.f.: Product_{k>=1} 1/(1 - x^k)^(k!!). a(n) ~ n!!. - Vaclav Kotesovec, Dec 25 2016 MATHEMATICA nmax = 31; CoefficientList[Series[Product[1/(1 - x^k)^(k!!), {k, 1, nmax}], {x, 0, nmax}], x] CROSSREFS Cf. A006882, A107895. Sequence in context: A231184 A291227 A027415 * A151503 A319789 A007718 Adjacent sequences:  A280085 A280086 A280087 * A280089 A280090 A280091 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Dec 25 2016 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 14 21:22 EST 2018. Contains 318138 sequences. (Running on oeis4.)