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 A206940 #7 Jul 22 2025 19:49:37 %S A206940 54,2916,28081,783557,20054092,348614952,8138711727,180107729045, %T A206940 3670799062946,80941950903896,1744792238104043,37022171557304461, %U A206940 801688023085812936,17220005386273509432,368962831518287162081 %N A206940 Number of 7Xn 0..1 arrays avoiding 0 0 0 horizontally and 0 1 1 vertically. %C A206940 Row 7 of A206936 %H A206940 R. H. Hardin, <a href="/A206940/b206940.txt">Table of n, a(n) for n = 1..210</a> %e A206940 Some solutions for n=4 %e A206940 ..1..0..0..1....1..1..0..0....1..0..1..0....0..0..1..0....1..0..1..0 %e A206940 ..0..1..1..0....1..0..0..1....1..1..0..0....0..0..1..1....0..0..1..1 %e A206940 ..1..0..0..1....1..0..1..0....1..0..1..0....0..1..1..0....0..0..1..0 %e A206940 ..0..1..1..0....1..1..0..1....1..0..0..1....0..0..1..1....0..0..1..1 %e A206940 ..1..0..0..1....0..0..1..0....0..1..1..0....0..1..0..0....1..1..0..0 %e A206940 ..0..0..1..0....1..1..0..0....1..0..0..1....0..0..1..1....0..0..1..0 %e A206940 ..0..1..0..1....0..0..1..1....0..1..0..0....0..1..0..0....1..0..0..1 %K A206940 nonn %O A206940 1,1 %A A206940 _R. H. Hardin_ Feb 13 2012