A013204 - OEIS

%I #26 Oct 19 2018 17:39:02

%S 0,1,-2,7,-24,165,-1232,10827,-111104,1316585,-17449472,257028847,

%T -4164086784,73616009805,-1409671718912,29070305745267,

%U -642304219480064,15137914082015825,-379068532960919552,10050622525103392087,-281286704647327186944

%N E.g.f. log(sech(x) + tan(x)).

%H Matthew House, <a href="/A013204/b013204.txt">Table of n, a(n) for n = 0..422</a>

%e Log(sech(x) + tan(x)) = x -2/2!*x^2 +7/3!*x^3 -24/4!*x^4 +165/5!*x^5 - ...

%t a[n_] := SeriesCoefficient[Log[Sech[x] + Tan[x]], {x, 0, n}] n!;

%t With[{nn=20},CoefficientList[Series[Log[Sech[x]+Tan[x]],{x,0,nn}],x] Range[ 0,nn]!] (* _Harvey P. Dale_, Oct 19 2018 *)

%K sign

%O 0,3

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

%E a(0)=0 inserted by _Alois P. Heinz_, Jul 29 2015