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 A268998 #4 Feb 17 2016 07:29:56 %S A268998 16,126,849,6009,37987,244397,1506570,9258784,55904997,335264275, %T A268998 1991983545,11763490813,69051103048,403375829894,2346089237885, %U A268998 13593697842329,78497992061491,451930855824889,2594820580805818 %N A268998 Number of 4Xn binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. %C A268998 Row 4 of A268995. %H A268998 R. H. Hardin, <a href="/A268998/b268998.txt">Table of n, a(n) for n = 1..210</a> %F A268998 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 A268998 Some solutions for n=4 %e A268998 ..0..1..0..1. .0..1..0..0. .1..1..0..1. .1..0..0..0. .1..0..0..0 %e A268998 ..0..1..0..0. .1..0..0..1. .0..0..0..0. .1..0..1..1. .0..1..0..0 %e A268998 ..0..0..0..0. .1..0..0..0. .0..0..0..0. .0..0..0..0. .0..1..0..0 %e A268998 ..1..1..0..0. .0..1..0..0. .1..0..0..0. .0..1..0..1. .0..0..0..1 %Y A268998 Cf. A268995. %K A268998 nonn %O A268998 1,1 %A A268998 _R. H. Hardin_, Feb 17 2016