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 A297546 #4 Dec 31 2017 15:05:37 %S A297546 1,4,35,93,197,905,4617,17190,60751,249752,1059063,4222592,16594402, %T A297546 66999457,272610044,1096920548,4397739438,17715067000,71488573309, %U A297546 287925302744,1158665331861,4666508501343,18801789510992,75728618048706 %N A297546 Number of 3Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 or 3 neighboring 1s. %C A297546 Row 3 of A297544. %H A297546 R. H. Hardin, <a href="/A297546/b297546.txt">Table of n, a(n) for n = 1..210</a> %F A297546 Empirical: a(n) = 4*a(n-1) -4*a(n-2) +17*a(n-3) +22*a(n-4) -76*a(n-5) -55*a(n-6) -66*a(n-7) -151*a(n-8) +47*a(n-9) +101*a(n-10) -39*a(n-11) +43*a(n-12) +60*a(n-13) -21*a(n-14) +7*a(n-15) +2*a(n-16) +a(n-17) %e A297546 Some solutions for n=5 %e A297546 ..0..1..1..0..0. .1..1..0..1..1. .0..0..1..1..1. .1..1..1..1..0 %e A297546 ..1..0..1..1..0. .1..1..0..1..1. .0..1..0..1..0. .0..1..1..0..0 %e A297546 ..0..1..0..0..0. .1..1..0..0..0. .0..0..1..0..0. .0..0..0..0..0 %Y A297546 Cf. A297544. %K A297546 nonn %O A297546 1,2 %A A297546 _R. H. Hardin_, Dec 31 2017