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 A288959 #23 Feb 16 2025 08:33:48
%S A288959 0,18,288,1800,7200,22050,56448,127008,259200,490050,871200,1472328,
%T A288959 2384928,3726450,5644800,8323200,11985408,16901298,23392800,31840200,
%U A288959 42688800,56455938,73738368,95220000,121680000,154001250,193179168,240330888,296704800,363690450
%N A288959 a(n) = n^2*(n^2 - 1)^2/2.
%C A288959 Except for n = 2, gives the detour index of the n X n rook and rook complement graph.
%C A288959 Also the detour index of the n X n king and n X n queen graphs. - _Eric W. Weisstein_, Dec 16 2017
%H A288959 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DetourIndex.html">Detour Index</a>
%H A288959 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/KingGraph.html">King Graph</a>
%H A288959 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/QueenGraph.html">Queen Graph</a>
%H A288959 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RookComplementGraph.html">Rook Complement Graph</a>
%H A288959 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RookGraph.html">Rook Graph</a>
%H A288959 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7, -21, 35, -35, 21, -7, 1).
%F A288959 a(n) = n^2*(n^2 - 1)^2/2.
%F A288959 a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7).
%F A288959 G.f.: (-18*x^2*(1+x)*(1+8*x+x^2))/(-1+x)^7.
%F A288959 a(n) = 18 *A001249(n-2). - _R. J. Mathar_, Dec 17 2017
%t A288959 Table[n^2 (n^2 - 1)^2/2, {n, 20}]
%t A288959 LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 18, 288, 1800, 7200, 22050, 56448}, 20]
%t A288959 CoefficientList[Series[-((18 x (1 + x) (1 + 8 x + x^2))/(-1 + x)^7), {x, 0, 20}], x]
%t A288959 18 Binomial[Range[0, 20] + 2, 3]^2 (* _Eric W. Weisstein_, Dec 20 2017 *)
%o A288959 (PARI) a(n) = n^2*(n^2-1)^2/2; \\ _Altug Alkan_, Dec 20 2017
%K A288959 nonn,easy
%O A288959 1,2
%A A288959 _Eric W. Weisstein_, Jun 20 2017