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 A207889 #7 Jul 22 2025 20:56:25 %S A207889 35,1225,2233,14825,49586,119278,618202,2332602,6535778,28238814, %T A207889 110355600,342679500,1341016198,5237625812,17405443410,64898151922, %U A207889 250040973048,867290958802,3166736891794,12011520072686,42745544469774 %N A207889 Number of 7Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 1 1 and 1 1 0 vertically. %C A207889 Row 7 of A207885 %H A207889 R. H. Hardin, <a href="/A207889/b207889.txt">Table of n, a(n) for n = 1..210</a> %e A207889 Some solutions for n=4 %e A207889 ..0..1..0..0....1..0..0..1....0..0..1..0....0..0..1..0....1..1..0..0 %e A207889 ..0..1..1..1....0..1..1..0....1..0..0..1....1..1..0..0....1..0..0..1 %e A207889 ..1..1..0..0....1..0..0..1....0..0..1..0....0..0..1..0....1..1..1..0 %e A207889 ..0..1..1..1....0..1..1..0....1..0..0..1....1..0..0..1....1..0..0..1 %e A207889 ..0..1..0..0....1..0..0..1....0..1..0..0....0..1..1..0....1..1..1..0 %e A207889 ..1..1..0..0....0..0..1..0....1..0..0..1....1..0..0..1....1..0..0..1 %e A207889 ..0..1..0..0....0..1..0..0....0..0..1..0....0..1..1..0....1..1..1..0 %K A207889 nonn %O A207889 1,1 %A A207889 _R. H. Hardin_ Feb 21 2012