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 A187646 (Signless) Central Stirling numbers of the first kind s(2n,n). 19
 1, 1, 11, 225, 6769, 269325, 13339535, 790943153, 54631129553, 4308105301929, 381922055502195, 37600535086859745, 4070384057007569521, 480544558742733545125, 61445535102359115635655, 8459574446076318147830625, 1247677142707273537964543265, 196258640868140652967646352465 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Number of permutations with n cycles on a set of size 2n. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA Asymptotic: a(n) ~ (2*n/(e*z*(1-z)))^n*sqrt((1-z)/(2*Pi*n*(2z-1))), where z=0.715331862959... is a root of the equation z = 2*(z-1)*log(1-z). - Vaclav Kotesovec, May 30 2011 MAPLE seq(abs(Stirling1(2*n, n)), n=0..20); MATHEMATICA Table[Abs[StirlingS1[2n, n]], {n, 0, 12}] N[1 + 1/(2 LambertW[-1, -Exp[-1/2]/2]), 50] (* The constant z in the asymptotic - Vladimir Reshetnikov, Oct 08 2016 *) PROG (Maxima) makelist(abs(stirling1(2*n, n)), n, 0, 12); (PARI) for(n=0, 50, print1(abs(stirling(2*n, n, 1)), ", ")) \\ G. C. Greubel, Nov 09 2017 CROSSREFS Cf. A008275, A007820, A187235, A237993, A242676, A285862. Sequence in context: A089917 A294388 A281257 * A347482 A170948 A245076 Adjacent sequences: A187643 A187644 A187645 * A187647 A187648 A187649 KEYWORD nonn,easy AUTHOR Emanuele Munarini, Mar 12 2011 STATUS approved

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Last modified August 6 12:02 EDT 2024. Contains 374974 sequences. (Running on oeis4.)