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 A283574 #4 Mar 11 2017 08:19:25 %S A283574 0,16,169,674,4313,21186,104464,513458,2431143,11478378,53471911, %T A283574 246887096,1132514276,5160569268,23395062541,105570183858, %U A283574 474452680669,2124725208078,9484785230640,42219767106150,187451695326747 %N A283574 Number of 3Xn 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 A283574 Row 3 of A283572. %H A283574 R. H. Hardin, <a href="/A283574/b283574.txt">Table of n, a(n) for n = 1..210</a> %F A283574 Empirical: a(n) = 4*a(n-1) +10*a(n-2) -6*a(n-3) -105*a(n-4) -108*a(n-5) -85*a(n-6) -14*a(n-7) -250*a(n-8) +176*a(n-9) -145*a(n-10) +44*a(n-11) -4*a(n-12) %e A283574 Some solutions for n=4 %e A283574 ..1..1..0..1. .0..1..0..0. .0..1..1..0. .0..0..0..0. .1..0..1..0 %e A283574 ..1..0..0..0. .0..1..0..0. .1..0..0..0. .0..1..1..0. .1..0..0..1 %e A283574 ..0..0..1..0. .1..1..0..1. .1..0..1..0. .0..1..0..1. .1..0..1..0 %Y A283574 Cf. A283572. %K A283574 nonn %O A283574 1,2 %A A283574 _R. H. Hardin_, Mar 11 2017