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 A194995 #8 Jul 22 2025 12:39:36 %S A194995 6,18,90,672,7858,138956,3816148,159427052,10305467946,1016480307410, %T A194995 154783529107972,36032460970618398,12930394865167766832, %U A194995 7102572782942842968972,6007897214058607933844528 %N A194995 Number of lower triangles of an n X n 0..5 array with each element differing from all of its horizontal and vertical neighbors by one. %C A194995 Column 5 of A194998 %H A194995 R. H. Hardin, <a href="/A194995/b194995.txt">Table of n, a(n) for n = 1..22</a> %e A194995 Some solutions for 4X4 %e A194995 ..1........4........2........1........1........3........2........4 %e A194995 ..2.3......3.4......3.4......2.3......2.1......4.5......3.2......5.4 %e A194995 ..3.2.1....4.3.4....2.3.2....3.2.3....1.2.3....5.4.3....2.3.4....4.3.2 %e A194995 ..4.3.2.1..5.4.3.2..3.4.3.4..4.3.4.3..2.1.2.1..4.5.4.5..3.4.5.4..3.2.1.0 %K A194995 nonn %O A194995 1,1 %A A194995 _R. H. Hardin_ Sep 07 2011