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 A268889 #4 Feb 15 2016 11:36:23 %S A268889 0,71,462,4133,27130,186732,1187838,7529253,46440962,283673207, %T A268889 1710265892,10226321520,60660804228,357586190291,2096177689750, %U A268889 12229766790505,71054027831574,411303965509420,2373090804832634 %N A268889 Number of 4Xn binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once. %C A268889 Row 4 of A268886. %H A268889 R. H. Hardin, <a href="/A268889/b268889.txt">Table of n, a(n) for n = 1..210</a> %F A268889 Empirical: a(n) = 2*a(n-1) +39*a(n-2) +14*a(n-3) -482*a(n-4) -1102*a(n-5) -111*a(n-6) +1758*a(n-7) +982*a(n-8) -1114*a(n-9) -743*a(n-10) +394*a(n-11) +206*a(n-12) -90*a(n-13) -17*a(n-14) +10*a(n-15) -a(n-16) %e A268889 Some solutions for n=4 %e A268889 ..0..0..0..0. .1..0..1..0. .1..0..0..1. .1..0..0..0. .0..1..0..1 %e A268889 ..0..0..1..0. .0..0..0..0. .1..0..1..0. .1..0..1..0. .1..0..0..1 %e A268889 ..0..0..1..0. .1..0..1..0. .1..0..0..1. .0..1..0..0. .0..1..0..0 %e A268889 ..0..1..0..1. .0..1..0..1. .0..1..0..0. .0..0..0..0. .0..0..0..0 %Y A268889 Cf. A268886. %K A268889 nonn %O A268889 1,2 %A A268889 _R. H. Hardin_, Feb 15 2016