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%I #15 Apr 02 2017 02:00:46
%S 1,-4,-79664,-627244864,-10054978651904,-281464457981584384,
%T -9106562752258155720704,743620567656757236530855936,
%U 627496952440053395297142177857536
%N Sin(tanh(x)*tan(x))/2 = Sum a(n)*x^(4*n+2)/(4*n+2)!.
%e sin(tanh(x)*tan(x))/2 = (1/2)*x^2 - (1/180)*x^6 - (4979/226800)*x^10 - (9800701/1362160800)*x^14 - (39277260359/
%e 25009272288000)*x^18 + ..., and (say) -(4979/226800)*10! = -79664 = a(2).
%t Sin[ Tanh[ x ]*Tan[ x ] ]/2 (* [ x^(4n+2) ] *)
%Y Cf. A012667.
%K sign
%O 0,2
%A _R. H. Hardin_
%E Extended with signs Mar 1997
%E Edited by _N. J. A. Sloane_, Apr 02 2017
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