A195949 - OEIS

%I #7 Dec 18 2015 18:17:46

%S 1,5,124,6466,957659,428469016,558025290154,2097314749929117,

%T 22849041981438170008,722512237126060035461636,

%U 66280377620551351708766528619,17635939684350970528621277455749104

%N Number of lower triangles of an n X n 0..2 array with no element greater than the number its nonzero horizontal and vertical neighbors

%H R. H. Hardin, <a href="/A195949/b195949.txt">Table of n, a(n) for n = 1..19</a>

%e Some solutions for n=4

%e ..0........0........1........0........0........1........1........1

%e ..1.0......1.0......1.1......1.1......1.1......2.1......1.2......1.1

%e ..1.1.1....1.0.1....1.2.0....2.1.1....1.2.0....2.1.1....1.2.0....1.1.0

%e ..0.1.0.0..2.2.2.1..1.2.1.0..1.2.2.0..0.2.1.1..2.2.1.1..1.2.1.0..2.2.0.0

%K nonn

%O 1,2

%A _R. H. Hardin_ Sep 25 2011