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 A323499 #13 Feb 16 2025 08:33:57
%S A323499 1,3,15,15,195,105,2625,945,38745,10395,634095,135135,11486475,
%T A323499 2027025,229053825,34459425,4996616625,654729075,118505962575,
%U A323499 13749310575,3038597637075,316234143225,83802047954625,7905853580625,2474532170735625,213458046676875
%N A323499 Number of minimum dominating sets in the n-triangular (Johnson) graph.
%H A323499 Andrew Howroyd, <a href="/A323499/b323499.txt">Table of n, a(n) for n = 2..200</a>
%H A323499 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/JohnsonGraph.html">Johnson Graph</a>
%H A323499 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimumDominatingSet.html">Minimum Dominating Set</a>
%H A323499 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularGraph.html">Triangular Graph</a>
%F A323499 a(n) = n!! for n odd.
%F A323499 a(n) = (n-1)!!*(1 + n*(n/2 - 1)) for n even. - _Andrew Howroyd_, Sep 08 2019
%o A323499 (PARI) a(n)={my(m=(n+1)\2); ((2*m)!/(m!*2^m))*if(n%2, 1, 1 + n*(n/2-1))} \\ _Andrew Howroyd_, Sep 08 2019
%Y A323499 Cf. A290716, A290847, A298104, A303048, A303227, A304561.
%K A323499 nonn
%O A323499 2,2
%A A323499 _Eric W. Weisstein_, Jan 16 2019
%E A323499 Terms a(14) and beyond from _Andrew Howroyd_, Sep 08 2019