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 A153365 #15 May 18 2025 19:36:09 %S A153365 8,28,100,360,1300,4700,17000,61500,222500,805000,2912500,10537500, %T A153365 38125000,137937500,499062500,1805625000,6532812500,23635937500, %U A153365 85515625000,309398437500,1119414062500,4050078125000,14653320312500 %N A153365 Number of zig-zag paths from top to bottom of a rectangle of width 9 with 2*n rows whose color is that of the top right corner. %H A153365 Joseph Myers, <a href="http://www.polyomino.org.uk/publications/2008/bmo1-2009-q1.pdf">BMO 2008--2009 Round 1 Problem 1---Generalisation</a> %F A153365 Empirical G.f.: x*(8-12*x)/(1-5*x+5*x^2). - _Colin Barker_, Jan 04 2012 %Y A153365 Cf. A153362, A153363, A153364, A153366, A153367. %K A153365 nonn,easy %O A153365 1,1 %A A153365 _Joseph Myers_, Dec 24 2008