A194535 Number of lower triangles of an n X n 0..3 array with new values introduced in row major order 0..3 and no element equal to more than one horizontal or vertical neighbor.

1, 4, 116, 16556, 7721920, 11525456507, 54979732214116, 838387866908847478, 40866499579695484000499, 6367568042830726931523028453, 3171485572844765112503023656979959

Offset: 1

Author

R. H. Hardin Aug 28 2011

Keywords

• nonn

Comments

Column 3 of A194540

Examples

			Some solutions for 3X3
..0......0......0......0......0......0......0......0......0......0......0
..1.2....1.1....1.2....1.2....1.1....1.2....1.2....1.2....1.0....1.2....1.1
..3.3.0..0.0.2..2.3.1..0.3.0..2.0.1..3.2.1..0.3.1..2.1.3..2.1.2..2.0.1..2.2.1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..12