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 A286871 #25 Feb 16 2025 08:33:45
%S A286871 2,5,43,647,22049,1455385,218691097,72877697369,51489351108548,
%T A286871 76986419992442614,244445556617038272066,1683765308911934025295376
%N A286871 Number of irredundant sets in the n X n king graph.
%H A286871 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IrredundantSet.html">Irredundant Set</a>
%H A286871 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/KingGraph.html">King Graph</a>
%t A286871 A286870 = Import["https://oeis.org/A286870/b286870.txt", "Table"][[All, 2]];
%t A286871 a[n_] := A286870[[2 n^2 - 2 n + 1]];
%t A286871 Table[a[n], {n, 1, 9}] (* _Jean-François Alcover_, Sep 23 2019 *)
%Y A286871 Main diagonal of A286870.
%Y A286871 Cf. A075550, A075709.
%K A286871 nonn,more
%O A286871 1,1
%A A286871 _Andrew Howroyd_, Aug 02 2017
%E A286871 a(10)-a(12) from _Christian Sievers_, Nov 22 2023