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 A297504 #4 Dec 31 2017 07:26:57 %S A297504 21,729,8803,191192,3624914,66289769,1272836591,23896899569, %T A297504 450529429259,8509989217247,160423654526876,3026744089971807, %U A297504 57099188342748031,1077069529621543033,20318551052028606846,383290619891741250595 %N A297504 Number of nX6 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 or 2 neighboring 1s. %C A297504 Column 6 of A297506. %H A297504 R. H. Hardin, <a href="/A297504/b297504.txt">Table of n, a(n) for n = 1..210</a> %e A297504 Some solutions for n=4 %e A297504 ..0..0..0..1..0..0. .0..0..0..0..1..1. .0..1..1..1..0..0. .1..1..1..0..1..0 %e A297504 ..0..0..1..0..0..1. .0..0..1..0..0..0. .0..0..0..0..1..1. .0..0..0..0..1..1 %e A297504 ..0..0..0..0..1..1. .0..1..1..0..0..0. .0..1..0..0..0..0. .0..1..0..0..0..0 %e A297504 ..0..1..1..0..1..0. .0..0..0..1..0..0. .1..0..0..1..1..1. .0..1..1..0..0..0 %Y A297504 Cf. A297506. %K A297504 nonn %O A297504 1,1 %A A297504 _R. H. Hardin_, Dec 31 2017