A208468 Number of 3Xn nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

5, 203, 20746, 4132120, 1358524513, 671329819215, 468215145028629, 440379520700561467, 539586833002472556426, 838156377510207185078132, 1614568986664304552415637091, 3787532565162728522045725351515

Offset: 1

Author

R. H. Hardin Feb 27 2012

Keywords

• nonn

Comments

Row 3 of A208466

Examples

			Some solutions for n=4
..0..0..0..0....0..1..2..0....0..0..0..0....0..0..0..0....0..1..0..1
..0..1..0..0....0..1..0..0....0..1..1..0....0..1..2..0....0..0..0..0
..1..0..1..0....0..0..1..0....0..1..0..2....1..0..0..0....1..1..1..0