A221291 Equals two maps: number of 3Xn binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..3 3Xn array.

1, 12, 92, 673, 5912, 48298, 396846, 3240527, 26241353, 211785583, 1703772887, 13679840407, 109689414233, 878752161168, 7035829547262, 56311795445487

Offset: 1

Author

R. H. Hardin Jan 09 2013

Keywords

• nonn

Comments

Row 3 of A221290

Examples

			Some solutions for n=3
..0..1..1....0..0..0....0..0..0....0..1..0....0..0..1....0..1..0....0..0..0
..0..1..0....1..1..0....0..1..0....0..0..1....0..1..0....0..0..0....0..0..1
..0..0..0....0..1..0....0..1..0....0..1..0....0..0..0....0..1..0....1..1..0