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 A013516 #18 Aug 07 2018 20:21:21 %S A013516 1,2,8,16,128,3840,15360,92160,1474560,185794560,3715891200,117964800, %T A013516 2831155200,51011754393600,13603134504960,8569974738124800, %U A013516 1371195958099968000,46620662575398912000,239763407530622976000 %N A013516 Denominators in the Taylor expansion exp(cosec(x)-cot(x))=1 + x/2 + x^2/8 + x^3/16 + 3*x^4/128 + 37*x^5/3840 + 59*x^6/15360 + ... %C A013516 The numerators are apparently the same as A047691. %F A013516 a(n) = A047692(n) * 2^n. - _Sean A. Irvine_, Aug 07 2018 %e A013516 exp(cosec(x)-cot(x)) = 1 +1*x/(2^1*1!) + 1*x^2/(2^2*2!) + 3*x^3/(2^3*3!) + 9*x^4/(2^4*4!) + 37*x^5/(2^5*5!) + 177*x^6/(2^6*6!) +959*x^7/(2^7*7!)+ ... %p A013516 A013516 := proc(n) %p A013516 exp(csc(x)-cot(x)) ; %p A013516 coeftayl( %,x=0,n) ; %p A013516 denom(%) ; %p A013516 end proc: # _R. J. Mathar_, Dec 18 2011 %Y A013516 Cf. A006229, A002425 (expansion of cosec(x)-cot(x)). %K A013516 nonn,frac %O A013516 0,2 %A A013516 Patrick Demichel (patrick.demichel(AT)hp.com) %E A013516 Corrected by _R. J. Mathar_, Dec 18 2011