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 A356366 #44 Jul 17 2025 14:51:14
%S A356366 1,2,5,18,523,44884,227838935,1086696880188,1566338449874827101,
%T A356366 694432397394116143569646
%N A356366 Number of (directed) circuits in the complete undirected graph on n labeled vertices.
%C A356366 In other words, number of closed trails up to cyclic rotations (cf. A357855).
%F A356366 a(n) = Sum_{k = 0..n(n-1)/2} A357887(n,k) = n + n * Sum_{k = 1..n(n-1)/2} A357885(n,k) / k.
%e A356366 For n = 3, we have 5 circuits: 3 of length 0 (singleton vertices), and 2 of length 3 (1->2->3->1 and 1->3->2->1).
%Y A356366 Cf. A007082, A135388, A232545, A350028, A357855, A357856, A357857, A357885, A357886, A357887.
%K A356366 nonn,more,walk
%O A356366 1,2
%A A356366 _Max Alekseyev_, Oct 16 2022
%E A356366 a(9) from _Bert Dobbelaere_, Oct 17 2022
%E A356366 a(10) from _Max Alekseyev_, Jul 17 2025