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 A194610 #6 Mar 15 2023 14:14:33 %S A194610 16,775,132214,86867366,214726600125,1988649454264015, %T A194610 69098146174647014753,9010212831798851496619501, %U A194610 4408846076603948466494884939778 %N A194610 Half the number of lower triangles of an (n+1) X (n+1) 0..3 array with no element equal to the average of its horizontal and vertical neighbors. %C A194610 Column 3 of A194615. %e A194610 Some solutions for 3 X 3 %e A194610 ..1......3......1......3......0......0......2......3......3......3......1 %e A194610 ..2.1....0.1....2.1....1.0....2.3....2.0....0.0....2.1....0.3....2.0....0.3 %e A194610 ..2.1.2..1.3.2..3.1.3..2.1.0..0.0.2..2.0.3..2.1.3..1.1.2..3.0.2..2.3.0..2.3.1 %Y A194610 Cf. A194615. %K A194610 nonn %O A194610 1,1 %A A194610 _R. H. Hardin_, Aug 30 2011