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 A201532 #8 Jul 22 2025 16:17:09 %S A201532 0,9,111,7799,2446147,3762507339,28456420346436 %N A201532 Number of n X n 0..2 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor. %C A201532 Diagonal of A201539 %e A201532 Some solutions for n=4 %e A201532 ..0..0..0..1....0..1..1..1....0..0..0..0....0..0..2..2....0..0..0..2 %e A201532 ..0..0..0..1....0..1..2..2....0..1..2..2....0..0..2..2....0..1..2..2 %e A201532 ..0..0..0..1....0..1..2..2....0..1..2..2....1..1..2..2....2..1..1..1 %e A201532 ..0..0..1..1....2..2..2..2....1..1..2..2....2..2..1..1....2..2..2..1 %K A201532 nonn %O A201532 1,2 %A A201532 _R. H. Hardin_ Dec 02 2011