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 A172222 #18 Feb 16 2025 08:33:11
%S A172222 1,70,406,1168,2948,6576,13122,23808,40168,63996,97344,142516,202072,
%T A172222 278828,375856,496484,644296,823132,1037088,1290516,1588024,1934476,
%U A172222 2334992,2794948,3319976
%N A172222 Number of ways to place 4 nonattacking zebras on a 4 X n board.
%C A172222 Zebra is a (fairy chess) leaper [2,3].
%H A172222 Vincenzo Librandi, <a href="/A172222/b172222.txt">Table of n, a(n) for n = 1..1000</a>
%H A172222 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 A172222 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ZebraGraph.html.html">Zebra Graph</a>
%H A172222 Wikipedia, <a href="https://en.wikipedia.org/wiki/Zebra_(chess)">Zebra (chess)</a>
%F A172222 a(n) = 4*(8*n^4 - 48*n^3 + 202*n^2 - 471*n + 507)/3, n>=9.
%F A172222 G.f.: -x * (4*x^12 -6*x^11 -2*x^10 -52*x^9 +160*x^8 -88*x^7 +2*x^6 -195*x^5 +473*x^4 -172*x^3 +66*x^2 +65*x +1) / (x-1)^5. - _Vaclav Kotesovec_, Mar 25 2010
%t A172222 CoefficientList[Series[-(4 x^12 - 6 x^11 - 2 x^10 - 52 x^9 + 160 x^8 - 88 x^7 + 2 x^6 - 195 x^5 + 473 x^4 - 172 x^3 + 66 x^2 + 65 x + 1) / (x - 1)^5, {x, 0, 50}], x] (* _Vincenzo Librandi_, May 28 2013 *)
%Y A172222 Cf. A172139, A061990, A172221.
%K A172222 nonn,easy
%O A172222 1,2
%A A172222 _Vaclav Kotesovec_, Jan 29 2010