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 A153363 #9 Jul 22 2025 06:17:08 %S A153363 5,8,16,28,56,100,200,360,720,1300,2600,4700,9400,17000,34000,61500, %T A153363 123000,222500,445000,805000,1610000,2912500,5825000,10537500, %U A153363 21075000,38125000,76250000,137937500,275875000,499062500,998125000,1805625000 %N A153363 Number of zig-zag paths from top to bottom of a rectangle of width 9 with n rows whose color is that of the top right corner. %H A153363 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 A153363 Empirical g.f.: x*(5+8*x-9*x^2-12*x^3+x^4)/(1-5*x^2+5*x^4). [_Colin Barker_, Sep 02 2012] %Y A153363 A153362, A153364, A153365, A153366, A153367 %K A153363 easy,nonn %O A153363 1,1 %A A153363 _Joseph Myers_, Dec 24 2008