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 A172230 #15 Feb 16 2025 08:33:11
%S A172230 0,2,61,405,1502,4072,9091,17791,31660,52442,82137,123001,177546,
%T A172230 248540,339007,452227,591736,761326,965045,1207197,1492342,1825296,
%U A172230 2211131,2655175,3163012,3740482,4393681,5128961,5952930,6872452,7894647
%N A172230 Number of ways to place 4 nonattacking wazirs on a 4 X n board.
%C A172230 Wazir is a (fairy chess) leaper [0,1].
%H A172230 Vincenzo Librandi, <a href="/A172230/b172230.txt">Table of n, a(n) for n = 1..1000</a>
%H A172230 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Number of ways of placing non-attacking queens and kings on boards of various sizes</a>
%H A172230 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GridGraph.html">Grid Graph</a>
%H A172230 Wikipedia, <a href="https://en.wikipedia.org/wiki/Wazir_(chess)">Wazir (chess)</a>
%F A172230 a(n) = (64*n^4 - 432*n^3 + 1235*n^2 - 1797*n + 1122)/6, n>=3.
%F A172230 G.f.: -x^2*(4*x^5+12*x^4+67*x^3+120*x^2+51*x+2)/(x-1)^5. - _Vaclav Kotesovec_, Mar 25 2010
%t A172230 CoefficientList[Series[- x (4 x^5 + 12 x^4 + 67 x^3 + 120 x^2 + 51 x + 2) / (x - 1)^5, {x, 0, 50}], x] (* _Vincenzo Librandi_, May 28 2013 *)
%Y A172230 Cf. A172227, A172229, A061990.
%K A172230 nonn,easy
%O A172230 1,2
%A A172230 _Vaclav Kotesovec_, Jan 29 2010
%E A172230 More terms from _Vincenzo Librandi_, May 28 2013