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 A297683 #4 Jan 03 2018 09:30:30 %S A297683 8,33,150,629,2790,12110,52889,230406,1005170,4382278,19110183, %T A297683 83327912,363357551,1584416863,6908888883,30126285845,131366174343, %U A297683 572824066436,2497808102429,10891729292407,47493549245614,207096331298600 %N A297683 Number of 3Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 1 or 4 neighboring 1s. %C A297683 Row 3 of A297682. %H A297683 R. H. Hardin, <a href="/A297683/b297683.txt">Table of n, a(n) for n = 1..210</a> %F A297683 Empirical: a(n) = 2*a(n-1) +7*a(n-2) +11*a(n-3) +17*a(n-4) -7*a(n-5) -10*a(n-6) -18*a(n-7) -a(n-8) %e A297683 Some solutions for n=7 %e A297683 ..0..1..0..0..0..0..1. .0..0..0..1..0..0..0. .0..0..1..0..0..0..1 %e A297683 ..1..0..0..0..0..1..1. .0..0..0..1..0..0..0. .1..0..0..0..0..0..0 %e A297683 ..0..0..0..0..1..0..1. .0..0..0..0..1..0..1. .1..0..1..1..0..0..1 %Y A297683 Cf. A297682. %K A297683 nonn %O A297683 1,1 %A A297683 _R. H. Hardin_, Jan 03 2018