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 A069447 #9 Apr 07 2021 18:41:41 %S A069447 256,1731840,3334295986,3616567402784 %N A069447 Half the number of n X 9 binary arrays with no path of adjacent 1's or adjacent 0's from top row to bottom row. %Y A069447 Cf. 2 X n A000079, n X 1 A000225, vertical path of 1 A069361-A069395, vertical paths of 0+1 A069396-A069416, vertical path of 1 not 0 A069417-A069428, no vertical paths A069429-A069447, no horizontal or vertical paths A069448-A069452. %K A069447 nonn %O A069447 2,1 %A A069447 _R. H. Hardin_, Mar 22 2002