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 A201247 #17 Aug 22 2024 14:29:25
%S A201247 0,0,2,552,29412,527654,5196928,34528698,173951172,714042302,
%T A201247 2503447216,7744201834,21635290132,55540293510,132752090192,
%U A201247 298491879178,636559136340,1296099575166,2533344878048,4774975629082,8712052571140,15436347060646,26634487077600
%N A201247 Number of ways to place 6 non-attacking ferses on an n X n board.
%C A201247 Fers is a leaper [1,1].
%H A201247 Vincenzo Librandi, <a href="/A201247/b201247.txt">Table of n, a(n) for n = 1..1000</a>
%H A201247 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, p.415
%H A201247 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (13, -78, 286, -715, 1287, -1716, 1716, -1287, 715, -286, 78, -13, 1).
%F A201247 a(n) = n^12/720 - 5n^10/48 + n^9/6 + 461n^8/144 - 29n^7/3 - 2147n^6/48 + 1289n^5/6 + 65807n^4/360 - 6356n^3/3 + 9185n^2/6 + 22834n/3 - 11478, n>=5.
%F A201247 G.f.: -2x^3*(41x^14 - 502x^13 + 2506x^12 - 7605x^11 + 18870x^10 - 41305x^9 + 60117x^8 - 21366x^7 - 73987x^6 + 52960x^5 + 237560x^4 + 93891x^3 + 11196x^2 + 263x + 1)/(x-1)^13.
%t A201247 CoefficientList[Series[- 2 x^2 (41 x^14 - 502 x^13 + 2506 x^12 - 7605 x^11 + 18870 x^10 - 41305 x^9 + 60117 x^8 - 21366 x^7 - 73987 x^6 + 52960 x^5 + 237560 x^4 + 93891 x^3 + 11196 x^2 + 263 x + 1)/(x-1)^13, {x, 0, 40}], x] (* _Vincenzo Librandi_, Apr 30 2013 *)
%Y A201247 Cf. A176886, A201243, A201244, A201245, A201246, A201248.
%K A201247 nonn,easy
%O A201247 1,3
%A A201247 _Vaclav Kotesovec_, Nov 28 2011