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%I #11 Sep 16 2023 13:59:33
%S 2,-8,-159328,-1254489728,-20109957303808,-562928915963168768,
%T -18213125504516311441408,1487241135313514473061711872
%N Expansion of sin(tanh(x)*tan(x)).
%F G.f.: sin(tanh(x)*tan(x)).
%F (* [ x^(4n+2) ] *)
%e sin(tanh(x)*tan(x)) = 2/2!*x^2-8/6!*x^6-159328/10!*x^10...
%t With[{nn=30},Take[CoefficientList[Series[Sin[Tanh[x]Tan[x]],{x,0,nn}],x] Range[0,nn]!,{3,-1,4}]] (* _Harvey P. Dale_, Sep 16 2023 *)
%K sign
%O 0,1
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Corrected by and prior Mathematica program replaced by _Harvey P. Dale_, Sep 16 2023