This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A009080 #16 Jul 24 2018 21:23:42
%S A009080 1,0,-12,-240,-5936,-155520,-65472,981903104,223580862720,
%T A009080 46255608778752,10060678641587200,2368138744630923264,
%U A009080 601490101481648443392,161192778898870464512000,43208403753541588946141184
%N A009080 Expansion of e.g.f. cos(x*tan(x)), even terms only.
%H A009080 G. C. Greubel, <a href="/A009080/b009080.txt">Table of n, a(n) for n = 0..240</a>
%e A009080 cos(x*tan(x)) = 1/0! +0*x^2/2! -12*x^4/4! -240*x^6/6! -5936*x^8/8! -...
%t A009080 With[{nmax = 60}, CoefficientList[Series[Cos[x*Tan[x]], {x, 0, nmax}], x]*Range[0, nmax]!][[1 ;; -1 ;; 2]] (* _G. C. Greubel_, Jul 24 2018 *)
%o A009080 (PARI) x='x+O('x^60); v=Vec(serlaplace(cos(x*tan(x)))); vector(#v\2,n,v[2*n-1]) \\ _G. C. Greubel_, Jul 24 2018
%K A009080 sign
%O A009080 0,3
%A A009080 _R. H. Hardin_
%E A009080 Extended with signs by _Olivier Gérard_, Mar 15 1997