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 A302261 #4 Apr 04 2018 12:47:37 %S A302261 8,105,772,5922,45717,353229,2727755,21069318,162753849,1257225302, %T A302261 9711792270,75021745843,579529894725,4476770505137,34582309009590, %U A302261 267142643360807,2063633101348406,15941227812038514,123143376763267969 %N A302261 Number of nX4 0..1 arrays with every element equal to 0, 1, 2 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero. %C A302261 Column 4 of A302265. %H A302261 R. H. Hardin, <a href="/A302261/b302261.txt">Table of n, a(n) for n = 1..210</a> %F A302261 Empirical: a(n) = 9*a(n-1) -2*a(n-2) -51*a(n-3) -80*a(n-4) -11*a(n-5) +262*a(n-6) +1203*a(n-7) -73*a(n-8) -847*a(n-9) -3807*a(n-10) +103*a(n-11) -606*a(n-12) +4295*a(n-13) +1436*a(n-14) +1630*a(n-15) -3052*a(n-16) +576*a(n-17) for n>18 %e A302261 Some solutions for n=5 %e A302261 ..0..0..1..0. .0..1..1..1. .0..0..1..1. .0..1..1..1. .0..0..1..0 %e A302261 ..0..0..0..1. .0..1..0..0. .0..0..1..1. .1..1..0..0. .1..0..1..1 %e A302261 ..1..1..1..1. .0..1..0..0. .1..1..0..0. .0..1..0..0. .0..1..0..1 %e A302261 ..1..0..0..0. .1..1..0..0. .0..0..1..1. .0..1..1..1. .0..1..0..1 %e A302261 ..0..1..1..1. .1..0..0..1. .1..0..1..0. .0..0..0..0. .1..0..1..0 %Y A302261 Cf. A302265. %K A302261 nonn %O A302261 1,1 %A A302261 _R. H. Hardin_, Apr 04 2018