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 A283573 #6 Mar 11 2017 16:15:20 %S A283573 0,4,26,72,282,908,2832,8856,26750,80088,237190,695272,2024064, %T A283573 5853676,16835874,48194664,137385394,390201476,1104636144,3118021376, %U A283573 8778028806,24653647608,69091665822,193246772832,539525988960,1503796131028 %N A283573 Number of 2Xn 0..1 arrays with no 1 equal to more than one of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly one element. %C A283573 Row 2 of A283572. %H A283573 R. H. Hardin, <a href="/A283573/b283573.txt">Table of n, a(n) for n = 1..210</a> %F A283573 Empirical: a(n) = 2*a(n-1) +5*a(n-2) +2*a(n-3) -17*a(n-4) -24*a(n-5) -16*a(n-6). %F A283573 Empirical: G.f.: 2*x^2*(2+9*x)/(-1+x+3*x^2+4*x^3)^2 . - _R. J. Mathar_, Mar 11 2017 %e A283573 Some solutions for n=4 %e A283573 ..0..0..1..1. .0..0..0..0. .1..1..0..0. .1..0..1..1. .0..1..1..1 %e A283573 ..0..1..0..1. .0..1..1..1. .1..0..0..0. .1..0..0..1. .0..1..0..1 %Y A283573 Cf. A283572. %K A283573 nonn %O A283573 1,2 %A A283573 _R. H. Hardin_, Mar 11 2017