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 A213987 #6 Jul 22 2025 23:05:53 %S A213987 3,92,14030,9131098,22406574462 %N A213987 Number of n X n 0..5 matrices whose square is also a 0..5 matrix. %C A213987 Column 5 of A213990 %e A213987 Some solutions for n=3 %e A213987 ..0..5..0....0..3..1....0..1..1....0..3..4....0..4..5....0..3..1....0..4..4 %e A213987 ..0..0..0....0..0..0....0..0..5....1..0..0....0..0..0....0..0..0....0..0..1 %e A213987 ..0..0..0....0..0..2....0..0..0....0..0..1....0..0..0....0..4..0....0..1..0 %K A213987 nonn %O A213987 1,1 %A A213987 _R. H. Hardin_ Jun 30 2012