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 A195590 #13 Aug 17 2024 15:28:00 %S A195590 8,32,100,276,708,1732,4100,9476,21508,48132,106500,233476,507908, %T A195590 1097732,2359300,5046276,10747908,22806532,48234500,101711876, %U A195590 213909508,448790532,939524100,1962934276,4093640708,8522825732,17716740100,36775657476,76235669508 %N A195590 Number of ways to place 2n nonattacking kings on a vertical cylinder 4 X 2n. %C A195590 Vertical cylinder: a chessboard where it is supposed that the columns 1 and 4 are in contact (number of columns = 4, number of rows = 2n). %H A195590 Ray Chandler, <a href="/A195590/b195590.txt">Table of n, a(n) for n = 1..3307</a> %H A195590 V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a> %H A195590 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5, -8, 4). %F A195590 Recurrence: a(n) = 4*a(n-3) - 8*a(n-2) + 5*a(n-1). %F A195590 G.f.: -(1+3*x)/((x-1)*(2*x-1)^2). %F A195590 Explicit formula: a(n) = (5*n-3)*2^n + 4. %Y A195590 Cf. A194644, A061593, A137432. %K A195590 nonn %O A195590 1,1 %A A195590 _Vaclav Kotesovec_, Sep 21 2011