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 A297851 #6 May 03 2020 15:38:25 %S A297851 0,3,15,30,45,131,181,298,430,1022,1429,2164,2135,4620,3680,9110, %T A297851 11981,9540,87199,22330,77938,182912,34081 %N A297851 Number of n X n 0..1 arrays with every element equal to 1, 2 or 4 king-move adjacent elements, with upper left element zero. %C A297851 Diagonal of A297858. %e A297851 Some solutions for n=7 %e A297851 ..0..0..1..1..1..0..1. .0..0..1..1..0..1..0. .0..1..1..0..0..1..1 %e A297851 ..1..1..0..0..0..1..0. .1..1..0..0..1..0..0. .1..0..0..1..1..0..0 %e A297851 ..0..1..1..1..1..1..0. .0..0..0..1..0..1..1. .0..1..0..0..0..0..1 %e A297851 ..0..1..0..0..0..1..1. .1..1..0..1..0..0..0. .0..1..0..1..1..0..1 %e A297851 ..0..1..1..1..1..0..0. .0..1..0..0..1..0..1. .0..1..0..0..0..0..1 %e A297851 ..1..1..0..0..0..0..1. .1..0..1..0..1..0..1. .1..0..0..1..1..0..0 %e A297851 ..0..0..1..1..1..0..1. .1..0..0..0..1..0..1. .0..1..1..0..0..1..1 %Y A297851 Cf. A297858. %K A297851 nonn %O A297851 1,2 %A A297851 _R. H. Hardin_, Jan 07 2018