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!)
 A083384 a(n) = n*Sum(((k-1)/2)*k!*Stirling_2(n,k),k=1..n). 2
 0, 2, 27, 316, 3825, 49866, 706923, 10899512, 182218005, 3289724710, 63865092159, 1327750936788, 29447495757225, 694257067232834, 17343019158929235, 457695211932767344, 12726295039220109885, 371902424983010438238, 11396594412860395106151, 365458808048854606362380 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA Equals A083385(n) - n*A000670(n). E.g.f.: x*(exp(x)-1)*exp(x)/(2-exp(x))^3. - Vladeta Jovovic, Sep 14 2003 a(n) ~ n! * n^2 / (8 * (log(2))^(n+2)). - Vaclav Kotesovec, Feb 18 2017 MATHEMATICA a[n_] := n Sum[1/2 (k-1) k! StirlingS2[n, k], {k, 1, n}]; Array[a, 20] (* Jean-François Alcover, Sep 01 2018 *) Rest[Range[0, 19]! CoefficientList[Series[x (Exp[x] - 1) Exp[x] / (2 - Exp[x])^3, {x, 0, 19}], x]] (* Vincenzo Librandi, Sep 01 2018 *) PROG (MAGMA) [n*&+[(k-1)/2*Factorial(k)*StirlingSecond(n, k): k in [0..n]]: n in [1..25]]; //  Vincenzo Librandi, Sep 01 2018 CROSSREFS Cf. A000670, A083385, A083411, A083410. Sequence in context: A220530 A199021 A091709 * A121971 A278790 A277832 Adjacent sequences:  A083381 A083382 A083383 * A083385 A083386 A083387 KEYWORD nonn AUTHOR N. J. A. Sloane, Jun 07 2003 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 14:37 EST 2018. Contains 318098 sequences. (Running on oeis4.)