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 A297389 #6 May 03 2020 15:29:22 %S A297389 1,5,19,126,3175,99682,4279111,540319235,108762242579,33338094951563, %T A297389 23051383345794169,28507330662583210289,58989477569892970363690, %U A297389 240856095225813296736743615 %N A297389 Number of n X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 neighboring 1. %C A297389 Diagonal of A297395. %e A297389 Some solutions for n=5 %e A297389 ..0..0..0..1..0. .0..0..0..1..1. .1..1..0..0..0. .0..1..0..0..0 %e A297389 ..0..0..1..0..0. .1..0..0..0..0. .0..0..0..0..1. .1..0..0..0..0 %e A297389 ..0..0..0..0..0. .0..1..0..1..1. .0..0..0..1..0. .0..0..0..0..0 %e A297389 ..0..1..0..1..1. .0..1..0..0..0. .0..1..0..0..0. .0..1..0..1..0 %e A297389 ..1..0..0..0..0. .0..0..1..0..0. .1..0..0..0..0. .1..0..0..0..1 %Y A297389 Cf. A297395. %K A297389 nonn %O A297389 1,2 %A A297389 _R. H. Hardin_, Dec 29 2017