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 A207687 #7 Jul 22 2025 20:40:35 %S A207687 25,625,1292,4174,9450,25076,65564,171382,433468,1150747,2968284, %T A207687 7722348,19756486,52194634,134386810,348854340,903166514,2358439491, %U A207687 6101183894,15824652924,41067569740,106834907856,276798237718,718012247867 %N A207687 Number of 7Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 1 1 vertically. %C A207687 Row 7 of A207682 %H A207687 R. H. Hardin, <a href="/A207687/b207687.txt">Table of n, a(n) for n = 1..210</a> %e A207687 Some solutions for n=4 %e A207687 ..0..1..1..0....0..1..0..0....1..1..0..0....0..0..1..0....1..0..0..1 %e A207687 ..1..0..0..1....0..1..1..0....0..1..1..1....0..1..0..0....0..1..0..0 %e A207687 ..1..1..1..1....0..0..1..0....1..0..0..1....0..1..1..0....1..0..0..1 %e A207687 ..0..0..1..0....0..1..0..0....1..1..1..0....0..0..1..0....0..1..0..0 %e A207687 ..1..1..0..0....0..0..1..0....0..0..1..0....0..1..0..0....1..0..0..1 %e A207687 ..0..0..1..0....0..1..1..0....1..1..0..0....0..1..1..0....0..1..0..0 %e A207687 ..0..0..1..0....0..1..0..0....0..1..0..0....0..0..1..0....1..1..0..0 %K A207687 nonn %O A207687 1,1 %A A207687 _R. H. Hardin_ Feb 19 2012