A194995 - OEIS

%I #6 Dec 18 2015 18:17:44

%S 6,18,90,672,7858,138956,3816148,159427052,10305467946,1016480307410,

%T 154783529107972,36032460970618398,12930394865167766832,

%U 7102572782942842968972,6007897214058607933844528

%N 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 Column 5 of A194998

%H R. H. Hardin, <a href="/A194995/b194995.txt">Table of n, a(n) for n = 1..22</a>

%e Some solutions for 4X4

%e ..1........4........2........1........1........3........2........4

%e ..2.3......3.4......3.4......2.3......2.1......4.5......3.2......5.4

%e ..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 ..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 nonn

%O 1,1

%A _R. H. Hardin_ Sep 07 2011