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 A369820 #7 Feb 16 2025 08:34:06
%S A369820 1,132,64988160,455760028510617600,128663499619046483713892580065280,
%T A369820 3352855075715829436523159831078082969600000000000000,
%U A369820 16066479367821778463055998145740101703072909829920380472524800000000000000000
%N A369820 Number of (undirected) Eulerian circuits on the complete graph K_{2n+1}.
%H A369820 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CompleteGraph.html">Complete Graph</a>
%H A369820 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/EulerianCycle.html">Eulerian Cycle</a>
%F A369820 a(n) = A135388(n)/2.
%Y A369820 Cf. A135388 (directed Eulerian circuits)
%K A369820 nonn
%O A369820 1,2
%A A369820 _Eric W. Weisstein_, Feb 02 2024