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 A069441 #13 Aug 23 2024 17:33:45 %S A069441 0,4,84,1074,11058,102448,896026,7578952,62820362,514178822, %T A069441 4174954460,33725176208,271523097884,2181288088576,17498432045552, %U A069441 140241880816930,1123280018219562,8993350007112124,71984384316723134,576073752326317448,4609640266662591130 %N A069441 Half the number of n X 3 binary arrays with no path of adjacent 1's or adjacent 0's from top row to bottom row. %F A069441 a(n) = 2^(3*n-1) - A069378(n) + A069403(n). - _Sean A. Irvine_, Aug 23 2024 %Y A069441 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 A069441 nonn,easy %O A069441 1,2 %A A069441 _R. H. Hardin_, Mar 22 2002 %E A069441 More terms from _Sean A. Irvine_, Aug 23 2024