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Expansion of e.g.f. log(sech(x) + tanh(x)).
1

%I #9 Oct 22 2023 11:38:11

%S 0,1,-2,3,-8,45,-272,1743,-13568,125625,-1290752,14554683,-181296128,

%T 2473184805,-36501112832,579439207623,-9859508338688,179018972217585,

%U -3453141256896512,70518070842040563

%N Expansion of e.g.f. log(sech(x) + tanh(x)).

%e x - 2/2!*x^2 + 3/3!*x^3 - 8/4!*x^4 + 45/5!*x^5 ...

%t With[{nn=20},CoefficientList[Series[Log[Sech[x]+Tanh[x]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Oct 22 2023 *)

%K sign

%O 0,3

%A Patrick Demichel (patrick.demichel(AT)hp.com)

%E a(0)=0 inserted and title improved by _Sean A. Irvine_, Aug 01 2018