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 A297501 #4 Dec 31 2017 07:24:39 %S A297501 4,31,110,531,2534,11405,53175,246040,1135117,5253716,24286811, %T A297501 112274796,519155469,2400230989,11097385328,51309028043,237225520918, %U A297501 1096808926323,5071081279846,23446053720513,108402467083427,501197081280420 %N A297501 Number of nX3 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 or 2 neighboring 1s. %C A297501 Column 3 of A297506. %H A297501 R. H. Hardin, <a href="/A297501/b297501.txt">Table of n, a(n) for n = 1..210</a> %F A297501 Empirical: a(n) = a(n-1) +5*a(n-2) +37*a(n-3) +63*a(n-4) +101*a(n-5) -45*a(n-6) -198*a(n-7) -254*a(n-8) -40*a(n-9) +88*a(n-10) +96*a(n-11) %e A297501 Some solutions for n=7 %e A297501 ..1..0..1. .1..1..0. .0..0..0. .1..1..0. .1..1..0. .0..1..0. .1..0..0 %e A297501 ..0..1..0. .0..0..0. .0..0..0. .0..0..1. .1..0..0. .1..1..1. .0..1..1 %e A297501 ..0..1..0. .1..0..0. .1..1..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0 %e A297501 ..1..1..1. .1..1..0. .0..0..0. .1..1..0. .0..1..1. .1..0..0. .1..1..1 %e A297501 ..0..0..0. .0..1..0. .0..0..0. .1..0..0. .0..0..0. .1..1..0. .0..1..0 %e A297501 ..0..1..0. .0..1..1. .1..1..0. .0..0..0. .0..1..0. .0..0..0. .0..1..0 %e A297501 ..0..1..1. .0..0..1. .0..0..0. .1..1..0. .1..0..0. .1..1..0. .1..0..1 %Y A297501 Cf. A297506. %K A297501 nonn %O A297501 1,1 %A A297501 _R. H. Hardin_, Dec 31 2017