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 A308648 #30 Jun 14 2019 19:26:31
%S A308648 0,0,1,3,12,40,120,336,7168,58752,345600,1682560,15983616,142192128,
%T A308648 2318697472,25614382080,282753361920,2645093410816,48869743454208,
%U A308648 674729909839872,12153962014842880,167314499427532800,1986101341059956736,20335611320801886208
%N A308648 Number of degree-n odd permutations of order dividing 8.
%F A308648 E.g.f.: (1/2)*exp(x + (1/2)*x^2 + (1/4)*x^4 + (1/8)*x^8) - (1/2)*exp(x - (1/2)*x^2 -(1/4)*x^4 - (1/8)*x^8).
%e A308648 For n=3 the a(3)=3 solutions are (1, 2), (1, 3), (2, 3) (permutations in cyclic notation).
%t A308648 With[{nn = 22},
%t A308648 CoefficientList[Series[1/2 Exp[x + x^2/2 + x^4/4 + x^8/8] - 1/2 Exp[x - x^2/2 - x^4/4 - x^8/8], {x, 0, nn}], x]*Range[0, nn]!]
%Y A308648 Cf. A061131, A061136, A061137.
%K A308648 easy,nonn
%O A308648 0,4
%A A308648 _Luis Manuel Rivera MartÃnez_, Jun 14 2019