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 A005801 Generalized tangent numbers of type 3^(2n+1). (Formerly M5218) 0
 0, 30, 217800, 16294301520, 6544151202877440, 9764950519194817858560, 42762698240957239228617722880, 466476501707480855594001261422438400, 11235366943887873286558941529247982529413120 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Ira M. Gessel, Symmetric functions and P-recursiveness, J. Combin. Theory Ser. A 53 (1990), no. 2, 257-285. FORMULA a(n) = 1/3^(2*n+1) * Sum_{i=0..2*n+1} (-1)^(i+1) * 2^-i * binomial(2*n+1, i) * A000182(n+i+1). a(n) ~ 2^(1/2)*3^(-1/2)*Pi^(-1/2)*n^(-1/2)*2^(8*n)*3^(-3*n)*{1 - 13/144*n^-1 + 169/41472*n^-2 + 48635/17915904*n^-3 - ...}. - Joe Keane (jgk(AT)jgk.org), Nov 07 2003 MATHEMATICA a000182[n_] := (4^n*(4^n-1)*Abs[BernoulliB[2*n]])/(2*n); a[n_] := Sum[((-1)^(i+1)*Binomial[2*n+1, i]*a000182[n+i+1])/2^i, {i, 0, 2*n+1}]/3^(2*n+1) CROSSREFS Cf. A000182 (tangent numbers). Sequence in context: A028668 A231815 A291995 * A079601 A238636 A140762 Adjacent sequences:  A005798 A005799 A005800 * A005802 A005803 A005804 KEYWORD nonn,easy AUTHOR EXTENSIONS Edited by Dean Hickerson, Dec 10 2002 More terms from Joe Keane (jgk(AT)jgk.org), Nov 07 2003 STATUS approved

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Last modified February 20 00:28 EST 2019. Contains 320329 sequences. (Running on oeis4.)