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%I M2188 #16 Dec 01 2018 07:58:25
%S 1,2,2248,54103952,9573516562048,7512502267832874752,
%T 19387585646491113265435648,134942950050961684035671842506752,
%U 2199105667698535717737352110310013698048
%N Generalized Euler numbers of type 3^2n.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Ira M. Gessel, <a href="http://dx.doi.org/10.1016/0097-3165(90)90060-A">Symmetric functions and P-recursiveness</a>, J. Combin. Theory Ser. A 53 (1990), no. 2, 257-285.
%F a(n) = (1/36^n) * Sum_{i=0..2*n} binomial(2*n, i) * A000364(n+i).
%t a[n_] := Sum[Binomial[2n, i]Abs[EulerE[2(n+i)]], {i, 0, 2n}]/36^n
%Y CF. A000364 (Euler numbers).
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, _Simon Plouffe_
%E Edited by _Dean Hickerson_, Dec 10 2002