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 A378279 #12 Nov 27 2024 12:33:36 %S A378279 0,0,1,4,20,160,910,5936,53424,397440,3304620,35023120,322852816 %N A378279 Number of subgroups of S_n isomorphic to S_3, where S_n is the n-th symmetric group. %F A378279 a(n) = (A281097(n) - A000085(n))/6. See A378163 for more information. %o A378279 (GAP) A378279 := function(n) %o A378279 local S; %o A378279 S := SymmetricGroup(n); %o A378279 return Sum(IsomorphicSubgroups(S, SymmetricGroup(3)), x->Index(S, Normalizer(S, Image(x)))); %o A378279 end; %Y A378279 Column k=3 of A378163. %Y A378279 Cf. A000085, A378280, A378281, A281097. %K A378279 nonn,hard,more %O A378279 1,4 %A A378279 _Jianing Song_, Nov 21 2024