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 A153373 #17 Jul 03 2023 11:07:38 %S A153373 5,18,66,244,906,3372,12566,46860,174810,652252,2433942,9083004, %T A153373 33897050,126503148,472111446,1761934444,6575609946,24540472572, %U A153373 91586214806,341804255580,1275630545370,4760717401612,17767238012502 %N A153373 Number of zig-zag paths from top to bottom of a rectangle of width 11 with 2n-1 rows whose color is not that of the top right corner. %H A153373 Joseph Myers, <a href="http://www.polyomino.org.uk/publications/2008/bmo1-2009-q1.pdf">BMO 2008--2009 Round 1 Problem 1---Generalisation</a> %H A153373 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6, -9, 2). %F A153373 Empirical G.f.: x*(5-12*x+3*x^2)/(1-6*x+9*x^2-2*x^3). - _Colin Barker_, Jan 04 2012 %Y A153373 Cf. A153368-A153372. %K A153373 nonn,easy %O A153373 1,1 %A A153373 _Joseph Myers_, Dec 24 2008