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 A297677 #6 Apr 20 2021 11:31:54 %S A297677 7,29,150,742,3744,18840,94891,477850,2406649,12120617,61043229, %T A297677 307433020,1548331209,7797889752,39272660089,197789648884, %U A297677 996131790595,5016837561113,25266394843590,127249627060291,640869727748787 %N A297677 Number of n X 3 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 1 or 4 neighboring 1's. %C A297677 Column 3 of A297682. %H A297677 R. H. Hardin, <a href="/A297677/b297677.txt">Table of n, a(n) for n = 1..210</a> %F A297677 Empirical: a(n) = 5*a(n-1) -a(n-2) +8*a(n-3) -5*a(n-4) -30*a(n-5) +17*a(n-6). %e A297677 Some solutions for n=7 %e A297677 ..1..0..1. .0..1..0. .0..0..0. .0..0..1. .1..0..1. .0..1..0. .1..0..1 %e A297677 ..1..0..0. .1..0..0. .0..0..1. .0..0..1. .1..0..0. .1..0..0. .1..0..0 %e A297677 ..1..0..0. .0..0..1. .0..0..1. .0..1..0. .0..0..0. .0..0..0. .1..1..1 %e A297677 ..0..1..0. .0..0..0. .1..0..0. .0..1..0. .0..0..1. .1..1..0. .1..0..0 %e A297677 ..0..0..0. .0..0..1. .1..0..0. .0..0..1. .1..0..1. .0..0..0. .1..0..1 %e A297677 ..0..1..0. .0..0..0. .1..0..0. .0..0..0. .0..1..0. .1..0..1. .0..0..0 %e A297677 ..0..1..0. .0..0..1. .0..0..1. .1..1..0. .1..0..1. .0..0..0. .0..1..1 %Y A297677 Cf. A297682. %K A297677 nonn %O A297677 1,1 %A A297677 _R. H. Hardin_, Jan 03 2018