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 A181951 #21 Jul 06 2018 17:10:55
%S A181951 0,0,1,7,31,121,526,2227,9283,54931,694156,6104011,76333687,872550043,
%T A181951 7491293356,49469173951,1571562887071,24729107440927,584036983443568,
%U A181951 8662243014551731,87570785839885951,1147293350653737211,66175018194591458692,1378758190497550145383
%N A181951 Number of cyclic subgroups of prime order in the Alternating Group A_n.
%H A181951 Andrew Howroyd, <a href="/A181951/b181951.txt">Table of n, a(n) for n = 1..200</a>
%F A181951 a(n) = A186202(n) - A001465(n). - _Andrew Howroyd_, Jul 04 2018
%t A181951 a[n_] := Sum[If[PrimeQ[p], Sum[If[p > 2 || Mod[k, 2] == 0, n!/(k!*(n - k*p)!*p^k)/(p - 1), 0], {k, 1, n/p}], 0], {p, 2, n}];
%t A181951 Array[a, 24] (* _Jean-François Alcover_, Jul 06 2018, after _Andrew Howroyd_ *)
%o A181951 (PARI) a(n)={sum(p=2, n, if(isprime(p), sum(k=1, n\p, if(p>2||k%2==0, n!/(k!*(n-k*p)!*p^k)))/(p-1)))}
%Y A181951 Cf. A001465, A181955, A186202 (symmetric group).
%K A181951 nonn
%O A181951 1,4
%A A181951 _Olivier Gérard_, Apr 03 2012
%E A181951 Terms a(9) and beyond from _Andrew Howroyd_, Jul 04 2018