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 A088042 #10 Feb 17 2014 06:06:15
%S A088042 1,2,4,4,16,76,232,106,946,5716,27776,63856,272416,2390480,10349536,
%T A088042 2027026,34459426,344594404,2618916472,10475679736,54997260256,
%U A088042 568305978472,3132225435824,1807129471456,12047128545376,175289251587776,1326384554695552
%N A088042 Number of permutations in the symmetric group S_n such that the size of their conjugacy class is odd.
%H A088042 Alois P. Heinz, <a href="/A088042/b088042.txt">Table of n, a(n) for n = 1..500</a>
%F A088042 a(n) = Sum_{k=0..floor(n/2)} n!/(n-2*k)!/k!/2^k*(C(n-(n mod 2), 2*k) mod 2). - _Vladeta Jovovic_, Nov 06 2003
%p A088042 a:= n-> n!*add((binomial(n-(n mod 2), 2*k) mod 2)/((n-2*k)!*k!*2^k),
%p A088042 k=0..floor(n/2)):
%p A088042 seq(a(n), n=1..30); # _Alois P. Heinz_, May 01 2013
%t A088042 a[n_] := n!*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 A088042 Cf. A088994, A060632.
%Y A088042 Cf. A000085, A001189.
%K A088042 nonn
%O A088042 1,2
%A A088042 Yuval Dekel (dekelyuval(AT)hotmail.com), Nov 02 2003
%E A088042 More terms from _Vladeta Jovovic_, Nov 03 2003