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 A181955 #15 Jul 03 2018 16:57:27
%S A181955 0,0,3,18,90,390,2205,10878,45318,256350,5530305,55869330,865551258,
%T A181955 9892489698,78223384785,470010394350,24530527675230,409760923017198,
%U A181955 10595007772540113,160826214447439770,1585844008081570650,16787211082925012730,1362379219330719093273
%N A181955 Weighted sum of all cyclic subgroups of prime order in the Alternating group.
%C A181955 Sum of p for all p-subgroups in Alt_n.
%H A181955 Andrew Howroyd, <a href="/A181955/b181955.txt">Table of n, a(n) for n = 1..200</a>
%F A181955 a(n) = A181954(n) - 2*A001465(n). - _Andrew Howroyd_, Jul 03 2018
%o A181955 (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/(p-1)))} \\ _Andrew Howroyd_, Jul 03 2018
%Y A181955 Cf. A181951 (number of such subgroups).
%Y A181955 Cf. A181954 (symmetric case).
%Y A181955 Cf. A001465.
%K A181955 nonn
%O A181955 1,3
%A A181955 _Olivier Gérard_, Apr 03 2012
%E A181955 Terms a(9) and beyond from _Andrew Howroyd_, Jul 03 2018