%I A005801 M5218
%S A005801 0,30,217800,16294301520,6544151202877440,9764950519194817858560,
%T A005801 42762698240957239228617722880,466476501707480855594001261422438400,
%U A005801 11235366943887873286558941529247982529413120
%N A005801 Generalized tangent numbers of type 3^(2n+1).
%D A005801 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A005801 Gessel, Ira M.; Symmetric functions and P-recursiveness. J. Combin. Theory 
               Ser. A 53 (1990), no. 2, 257-285.
%F A005801 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)
%F A005801 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
%t A005801 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)
%Y A005801 Sequence in context: A115459 A135421 A028668 this_sequence A079601 A159578 
               A140762
%Y A005801 Adjacent sequences: A005798 A005799 A005800 this_sequence A005802 A005803 
               A005804
%K A005801 nonn,easy
%O A005801 0,2
%A A005801 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A005801 Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Dec 10 2002
%E A005801 More terms from Joe Keane (jgk(AT)jgk.org), Nov 07 2003