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 A266125 #6 Apr 20 2020 19:42:04 %S A266125 1,9,77,572,62104,13689944,10444421518 %N A266125 Number of n X n integer arrays with each element equal to the number of horizontal, diagonal and antidiagonal neighbors exactly one smaller than itself. %C A266125 Diagonal of A266131. %e A266125 Some solutions for n=4 %e A266125 ..0..0..0..0....2..1..1..0....1..1..0..0....1..1..0..0....1..0..1..2 %e A266125 ..0..0..0..0....2..1..0..2....1..0..2..0....1..0..2..0....1..1..1..2 %e A266125 ..0..0..2..1....1..0..1..1....1..1..0..0....0..1..2..3....1..1..0..1 %e A266125 ..1..1..2..0....0..1..1..2....2..1..1..1....2..1..2..0....1..0..2..0 %Y A266125 Cf. A266131. %K A266125 nonn %O A266125 1,2 %A A266125 _R. H. Hardin_, Dec 21 2015