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 A194612 #9 Jun 04 2025 00:29:36 %S A194612 69,12438,12561823,73569838704,2481372954501732,481414314393133400117 %N A194612 Half the number of lower triangles of an (n+1) X (n+1) 0..5 array with no element equal to the average of its horizontal and vertical neighbors. %e A194612 Some solutions for 3X3 %e A194612 ..0......0......3......3......1......2......2......5......4......2......1 %e A194612 ..2.0....4.3....0.0....0.3....4.4....5.0....1.0....1.1....0.2....1.2....0.5 %e A194612 ..1.5.2..0.4.0..0.4.3..4.1.2..5.0.5..2.4.0..0.4.5..2.5.1..4.2.4..4.1.2..2.5.4 %Y A194612 Column 5 of A194615. %K A194612 nonn %O A194612 1,1 %A A194612 _R. H. Hardin_, Aug 30 2011