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 A069400 #9 Apr 07 2021 18:48:03 %S A069400 1,1219,587031,182702967,44515781333 %N A069400 Half the number of 7 X n binary arrays with a path of adjacent 1's and a path of adjacent 0's from top row to bottom row. %Y A069400 Cf. 1 X n A000225, 2 X n A016269, 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 A069400 nonn %O A069400 2,2 %A A069400 _R. H. Hardin_, Mar 22 2002