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 A194536 #7 Jul 07 2025 18:52:51 %S A194536 1,4,131,43785,79201795,627974590650,21399815343394998, %T A194536 3132305932642809585983,1969210116072259125767299138 %N A194536 Number of lower triangles of an n X n 0..4 array with new values introduced in row major order 0..4 and no element equal to more than one horizontal or vertical neighbor. %C A194536 Column 4 of A194540. %e A194536 Some solutions for 3 X 3 %e A194536 ..0......0......0......0......0......0......0......0......0......0......0 %e A194536 ..1.2....1.0....1.2....1.1....1.0....1.2....1.0....0.1....1.2....1.2....0.1 %e A194536 ..2.0.1..2.2.1..0.1.0..0.2.1..2.3.4..3.2.0..0.2.3..1.0.0..2.1.2..0.3.1..1.0.1 %Y A194536 Cf. A194540. %K A194536 nonn %O A194536 1,2 %A A194536 _R. H. Hardin_, Aug 28 2011