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 A283035 #6 Apr 26 2020 20:41:42 %S A283035 0,4,119,9152,1604067,706205768,797350288363,2355217281173760, %T A283035 18388049679475271526,382245292023510825419744 %N A283035 Number of n X n 0..1 arrays with no 1 equal to more than one of its horizontal and vertical neighbors, with the exception of exactly one element. %C A283035 Diagonal of A283042. %e A283035 Some solutions for n=4 %e A283035 ..1..1..0..0. .1..1..1..0. .0..1..0..0. .1..0..1..1. .0..0..1..0 %e A283035 ..0..0..0..1. .0..0..0..0. .0..0..0..1. .0..0..0..0. .0..0..1..1 %e A283035 ..1..0..1..0. .1..0..1..0. .1..1..0..0. .1..1..0..1. .0..0..1..0 %e A283035 ..0..1..1..1. .1..0..0..0. .1..0..1..0. .1..0..0..1. .0..1..0..1 %Y A283035 Cf. A283042. %K A283035 nonn %O A283035 1,2 %A A283035 _R. H. Hardin_, Feb 27 2017