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 A052361 #14 Feb 17 2014 06:05:41
%S A052361 0,0,2,20,104,644,4808,40214,361934,3623084,39889024,478937744,
%T A052361 6226748384,87175900720,1307664018464,20922787860974,355687393636574,
%U A052361 6402373361133596,121645097789915528,2432901997700960264,51090942116712179744,1124000727209301701528
%N A052361 Number of permutations in the symmetric group S_n such that the size of their conjugacy class is even.
%H A052361 Alois P. Heinz, <a href="/A052361/b052361.txt">Table of n, a(n) for n = 1..400</a>
%p A052361 a:= n-> n!*(1-add((binomial(n-(n mod 2), 2*k) mod 2)/((n-2*k)!*k!*2^k),
%p A052361 k=0..floor(n/2))):
%p A052361 seq(a(n), n=1..30); # _Alois P. Heinz_, May 01 2013
%t A052361 a[n_] := n!*(1-Sum[Mod[Binomial[n-Mod[n, 2], 2*k], 2]/((n-2*k)!*k!*2^k), {k, 0, Floor[n/2]}]); Table[a[n], {n, 1, 30}] (* _Jean-François Alcover_, Feb 17 2014, after _Alois P. Heinz_ *)
%Y A052361 a(n) = n! - A088042(n).
%K A052361 nonn
%O A052361 1,3
%A A052361 Yuval Dekel (dekelyuval(AT)hotmail.com), Nov 07 2003
%E A052361 More terms from _Ray Chandler_, Nov 10 2003