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 A207004 #7 Jul 22 2025 19:56:00 %S A207004 54,2916,61003,1124120,22816988,490003769,10432265840,218637649146, %T A207004 4572897018607,95971301545030,2016876598616899,42362715890770207, %U A207004 889374671577272079,18672246190599282488,392068641835583132666 %N A207004 Number of 7Xn 0..1 arrays avoiding 0 1 0 horizontally and 0 1 1 vertically. %C A207004 Row 7 of A207000 %H A207004 R. H. Hardin, <a href="/A207004/b207004.txt">Table of n, a(n) for n = 1..210</a> %e A207004 Some solutions for n=4 %e A207004 ..0..0..0..1....0..0..1..1....0..1..1..1....0..1..1..1....0..0..1..1 %e A207004 ..1..1..1..0....1..1..0..0....0..0..0..1....0..0..0..0....1..1..0..1 %e A207004 ..0..0..0..0....0..0..1..1....0..0..1..1....1..0..1..1....0..0..0..1 %e A207004 ..1..0..1..1....0..0..0..0....1..1..0..1....0..0..0..0....0..0..1..1 %e A207004 ..0..0..0..0....0..0..0..1....0..0..1..1....0..1..1..0....0..0..0..0 %e A207004 ..0..0..1..1....1..0..0..0....0..0..0..1....0..0..0..1....1..1..0..0 %e A207004 ..1..1..0..0....0..0..1..1....1..0..1..1....1..1..1..0....0..0..1..1 %K A207004 nonn %O A207004 1,1 %A A207004 _R. H. Hardin_ Feb 14 2012