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 A297550 #4 Dec 31 2017 15:08:35 %S A297550 1,69,8057,67215,754342,45293985,1610981344,33425081735,874581570077, %T A297550 29281129310008,859429362196818,23114288469712129,662232886527397803, %U A297550 19622752789142693265,564182183135035001141,16033004070256687706334 %N A297550 Number of 7Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 or 3 neighboring 1s. %C A297550 Row 7 of A297544. %H A297550 R. H. Hardin, <a href="/A297550/b297550.txt">Table of n, a(n) for n = 1..210</a> %e A297550 Some solutions for n=5 %e A297550 ..0..1..0..0..0. .0..0..0..1..0. .0..0..0..1..0. .0..0..0..0..0 %e A297550 ..1..0..1..1..0. .0..0..1..1..1. .0..0..1..0..1. .0..1..1..1..0 %e A297550 ..0..1..1..0..0. .1..1..0..0..0. .0..1..0..1..0. .1..0..0..1..1 %e A297550 ..0..0..0..1..0. .1..1..0..0..0. .1..1..0..0..1. .0..1..0..0..1 %e A297550 ..0..0..1..1..0. .0..0..0..1..1. .0..0..1..1..0. .0..0..1..1..0 %e A297550 ..0..0..0..1..1. .0..1..1..1..0. .1..1..0..0..0. .0..0..0..0..0 %e A297550 ..0..0..1..1..0. .0..0..1..0..0. .1..1..0..0..0. .0..0..0..0..0 %Y A297550 Cf. A297544. %K A297550 nonn %O A297550 1,2 %A A297550 _R. H. Hardin_, Dec 31 2017