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 A051695 #12 Feb 09 2020 14:28:34
%S A051695 0,0,0,0,0,90,630,3780,18900,94500,457380,3825360,31505760,312432120,
%T A051695 2704501800,22984481520,179863997040,1531709328240,13078616488560,
%U A051695 147223414987200,1657733805020160,20131890668255520,226464779237447520,2542924546378413120,27053572399079688000
%N A051695 Number of degree-n even permutations of order exactly 4.
%H A051695 Andrew Howroyd, <a href="/A051695/b051695.txt">Table of n, a(n) for n = 1..200</a>
%F A051695 a(n) = (A001473(n) + A051685(n))/2.
%F A051695 E.g.f.: (exp(x + x^2/2 + x^4/4) + exp(x - x^2/2 - x^4/4) - exp(x + x^2/2) - exp(x - x^2/2))/2. - _Andrew Howroyd_, Feb 01 2020
%t A051695 m = 26; ((Exp[x + x^2/2 + x^4/4] + Exp[x - x^2/2 - x^4/4] - Exp[x + x^2/2] - Exp[x - x^2/2])/2 + O[x]^m // CoefficientList[#, x]& // Rest) * Range[m - 1]! (* _Jean-François Alcover_, Feb 09 2020, after _Andrew Howroyd_ *)
%o A051695 (PARI) seq(n)={my(A=O(x*x^n)); Vec(serlaplace(exp(x + x^2/2 + x^4/4 + A) + exp(x - x^2/2 - x^4/4 + A) - exp(x + x^2/2 + A) - exp(x - x^2/2 + A))/2, -n)} \\ _Andrew Howroyd_, Feb 01 2020
%Y A051695 Cf. A001473, A048099, A051685.
%K A051695 easy,nonn
%O A051695 1,6
%A A051695 _Vladeta Jovovic_
%E A051695 Terms a(19) and beyond from _Andrew Howroyd_, Feb 01 2020