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 A220467 #14 May 11 2017 17:52:52 %S A220467 0,0,0,0,0,0,1601292,314949564,17143061738,423677826986,6210264633994, %T A220467 62831788827614,481992723228798,2982908737810114,15548436178142582, %U A220467 70420082692285198,283631426534134042,1034163399690010346,3461457325296584554,10754832937513676198 %N A220467 Number of ways to place 10 nonattacking kings on an n X n board. %H A220467 Vincenzo Librandi, <a href="/A220467/b220467.txt">Table of n, a(n) for n = 1..1000</a> %H A220467 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a> %F A220467 a(n) = n^20/3628800 - n^18/8960 + n^17/6720 + 353*n^16/17280 - 53*n^15/1008 - 29467*n^14/13440 + 11867*n^13/1440 + 25901053*n^12/172800 - 107495*n^11/144 - 8467959*n^10/1280 + 122792641*n^9/2880 + 32499630031*n^8/181440 - 112903333*n^7/72 - 16042907329*n^6/6720 + 36445613711*n^5/1008 - 1784819159*n^4/300 - 9997453897*n^3/21 + 85979117831*n^2/140 + 13635070421*n/5 - 5609601346, for n>=9. %F A220467 G.f.: -2*x^7*(97581*x^22 - 1758956*x^21 + 16320562*x^20 - 100734462*x^19 + 443795293*x^18 - 1471049082*x^17 + 3971393292*x^16 - 9304893422*x^15 + 17917931016*x^14 - 22612415810*x^13 + 6949925614*x^12 + 21430418050*x^11 + 9738010368*x^10 - 153051533038*x^9 + 256884162558*x^8 - 71451647970*x^7 - 265785285277*x^6 + 220345759446*x^5 + 251887022384*x^4 + 63841610284*x^3 + 5432696107*x^2 + 140661216*x + 800646)/(x-1)^21. %t A220467 Rest[CoefficientList[Series[-2*x^7*(97581*x^22 - 1758956*x^21 + 16320562*x^20 - 100734462*x^19 + 443795293*x^18 - 1471049082*x^17 + 3971393292*x^16 - 9304893422*x^15 + 17917931016*x^14 - 22612415810*x^13 + 6949925614*x^12 + 21430418050*x^11 + 9738010368*x^10 - 153051533038*x^9 + 256884162558*x^8 - 71451647970*x^7 - 265785285277*x^6 + 220345759446*x^5 + 251887022384*x^4 + 63841610284*x^3 + 5432696107*x^2 + 140661216*x + 800646)/(x-1)^21, {x, 0, 20}], x]] %Y A220467 Cf. A061995 (2 kings), A061996 (3 kings), A061997 (4 kings). %Y A220467 Cf. A061998 (5 kings), A172158 (6 kings), A194788 (7 kings). %Y A220467 Cf. A201369 (8 kings), A201771 (9 kings). %Y A220467 Column k=10 of A193580. %K A220467 nonn %O A220467 1,7 %A A220467 _Vaclav Kotesovec_, Dec 15 2012