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 A207899 #7 Jul 22 2025 20:57:28 %S A207899 26,676,2812,12040,49442,205258,856480,3559040,14795830,61589756, %T A207899 256239484,1065818440,4434375632,18449465050,76753459760,319315656274, %U A207899 1328477921238,5526925286486,22993687059966,95661297604612 %N A207899 Number of 6Xn 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 0 and 1 1 1 vertically. %C A207899 Row 6 of A207895 %H A207899 R. H. Hardin, <a href="/A207899/b207899.txt">Table of n, a(n) for n = 1..210</a> %e A207899 Some solutions for n=4 %e A207899 ..0..0..1..1....0..0..1..0....1..0..0..1....0..0..1..1....0..0..1..1 %e A207899 ..0..1..1..0....0..0..1..1....0..0..1..0....0..1..1..0....0..0..1..1 %e A207899 ..1..0..0..1....1..1..0..0....1..1..0..0....1..1..0..0....1..1..0..0 %e A207899 ..0..1..0..0....0..0..1..1....0..0..1..1....1..0..0..1....0..0..1..0 %e A207899 ..0..0..1..0....1..0..0..1....0..0..1..1....0..0..1..0....1..0..0..1 %e A207899 ..1..0..0..1....0..1..1..0....1..1..0..0....1..1..0..0....0..1..1..1 %K A207899 nonn %O A207899 1,1 %A A207899 _R. H. Hardin_ Feb 21 2012