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 A069424 #13 Aug 23 2024 08:39:50 %S A069424 1,65,1231,17339,217253,2575297,29682643,337104939,3798244149, %T A069424 42611591165,476921965419,5330934738199,59545502975241, %U A069424 664849480893793,7421696282496891,82838232515999423,924548372982432205,10318403957821437753,115156011527942405255 %N A069424 Number of n X 4 binary arrays with a path of adjacent 1's and no path of adjacent 0's from top row to bottom row. %F A069424 a(n) = A069379(n) - 2 * A069404(n). - _Sean A. Irvine_, Aug 23 2024 %Y A069424 Cf. 2 X n A001047, n X 2 A034182, 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 A069424 nonn %O A069424 1,2 %A A069424 _R. H. Hardin_, Mar 22 2002 %E A069424 More terms from _Sean A. Irvine_, Aug 23 2024