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 A382777 #6 Apr 05 2025 12:01:48
%S A382777 1,2,21,540,25740,1965600,219769200,33844456800,6868433880000,
%T A382777 1776393899280000,570349326947400000,222585024290428800000,
%U A382777 103769138324197906560000,56957727035726406489600000,36357688414546530128697600000,26705308554813693259046592000000,22364482036994885663848836864000000
%N A382777 Number of minimum total dominating sets in the (3n)-triangular honeycomb bishop graph.
%C A382777 The total domination number is 2*n.
%H A382777 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimumTotalDominatingSet.html">Minimum Total Dominating Set</a>.
%H A382777 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularHoneycombBishopGraph.html">Triangular Honeycomb Bishop Graph</a>.
%F A382777 a(n) = Sum_{k=0..n} binomial(2*n-k,k)*binomial(n+k,n-k)*(2*(n-k))!*(2*k)!/(2^n).
%F A382777 a(n) = A304564(3*n) for n > 0.
%o A382777 (PARI) a(n) = sum(k=0, n, binomial(2*n-k,k)*binomial(n+k,n-k)*(2*(n-k))!*(2*k)!)/(2^n)
%Y A382777 Row sums of A382776.
%Y A382777 Cf. A304564.
%K A382777 nonn
%O A382777 0,2
%A A382777 _Andrew Howroyd_, Apr 04 2025