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 A297396 #7 Feb 28 2019 06:22:40 %S A297396 1,9,19,37,127,323,763,2121,5557,14031,37065,97027,250371,653707, %T A297396 1706245,4431885,11544027,30085525,78290135,203852347,530958219, %U A297396 1382353401,3599332477,9373032927,24405570561,63547912011,165475162027,430875964651 %N A297396 Number of 3 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 neighboring 1. %H A297396 R. H. Hardin, <a href="/A297396/b297396.txt">Table of n, a(n) for n = 1..210</a> %F A297396 Empirical: a(n) = a(n-1) + a(n-2) + 8*a(n-3) + a(n-4) - 2*a(n-6). %F A297396 Empirical g.f.: x*(1 + 8*x + 9*x^2 + x^3 - 2*x^4 - 2*x^5) / (1 - x - x^2 - 8*x^3 - x^4 + 2*x^6). - _Colin Barker_, Feb 28 2019 %e A297396 Some solutions for n=5: %e A297396 ..0..0..0..1..1. .0..1..1..0..0. .0..0..0..1..0. .1..0..0..0..0 %e A297396 ..1..1..0..0..0. .0..0..0..0..0. .0..0..0..0..1. .0..1..0..0..0 %e A297396 ..0..0..0..1..1. .0..0..0..1..1. .0..0..0..0..0. .0..0..0..1..1 %Y A297396 Row 3 of A297395. %K A297396 nonn %O A297396 1,2 %A A297396 _R. H. Hardin_, Dec 29 2017