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 A303625 #4 Apr 27 2018 09:56:26 %S A303625 4,2,38,68,362,1283,5411,22516,96189,417555,1829258,8090336,35972626, %T A303625 160686336,719920275,3232692431,14538525542,65457371351,294941937573, %U A303625 1329700498750,5997079537476,27054800037678,122076548954830 %N A303625 Number of 3Xn 0..1 arrays with every element equal to 0, 2, 3, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A303625 Row 3 of A303624. %H A303625 R. H. Hardin, <a href="/A303625/b303625.txt">Table of n, a(n) for n = 1..210</a> %F A303625 Empirical: a(n) = 8*a(n-1) -9*a(n-2) -54*a(n-3) +79*a(n-4) +193*a(n-5) -246*a(n-6) -383*a(n-7) +307*a(n-8) +547*a(n-9) -250*a(n-10) -458*a(n-11) +174*a(n-12) +193*a(n-13) -66*a(n-14) -34*a(n-15) -3*a(n-16) for n>17 %e A303625 Some solutions for n=5 %e A303625 ..0..0..0..0..0. .0..0..1..0..1. .0..0..1..1..0. .0..1..1..1..1 %e A303625 ..0..0..0..0..1. .0..0..1..0..1. .0..0..0..1..1. .0..1..1..1..1 %e A303625 ..1..0..1..0..0. .1..0..0..0..0. .0..0..0..1..1. .1..1..0..1..1 %Y A303625 Cf. A303624. %K A303625 nonn %O A303625 1,1 %A A303625 _R. H. Hardin_, Apr 27 2018