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 A297684 #4 Jan 03 2018 09:31:13 %S A297684 16,98,742,4633,32911,221420,1519630,10322924,70546581,480682141, %T A297684 3279483836,22360879158,152513668108,1040062673807,7093214269529, %U A297684 48373908268204,329903456068580,2249876994245104,15343785763900111 %N A297684 Number of 4Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 1 or 4 neighboring 1s. %C A297684 Row 4 of A297682. %H A297684 R. H. Hardin, <a href="/A297684/b297684.txt">Table of n, a(n) for n = 1..210</a> %F A297684 Empirical: a(n) = 2*a(n-1) +20*a(n-2) +60*a(n-3) +184*a(n-4) +57*a(n-5) -73*a(n-6) -458*a(n-7) +105*a(n-8) +215*a(n-9) +380*a(n-10) -574*a(n-11) -435*a(n-12) +162*a(n-13) -270*a(n-14) -87*a(n-15) +32*a(n-16) +8*a(n-17) %e A297684 Some solutions for n=5 %e A297684 ..0..0..0..0..1. .1..0..0..0..1. .1..0..0..1..1. .1..0..0..1..1 %e A297684 ..0..0..1..0..1. .0..0..0..0..1. .1..0..0..0..0. .1..0..0..0..0 %e A297684 ..1..1..1..0..1. .1..1..1..0..0. .1..0..0..0..1. .0..1..0..1..0 %e A297684 ..1..0..0..0..1. .1..0..1..0..0. .0..1..0..1..0. .0..0..0..0..0 %Y A297684 Cf. A297682. %K A297684 nonn %O A297684 1,1 %A A297684 _R. H. Hardin_, Jan 03 2018