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 A069397 #9 Apr 07 2021 19:01:27 %S A069397 1,67,2427,66579,1565371,33438451,669776139,12817737731,237180629275, %T A069397 4277806868563,75628309151275,1315968756706339,22606389934281147, %U A069397 384286142618740851,6475978445076745163 %N A069397 Half the number of 4 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 A069397 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 A069397 nonn %O A069397 2,2 %A A069397 _R. H. Hardin_, Mar 22 2002