A220557 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly one horizontal or antidiagonal neighbor.

1, 5, 64, 3966, 810778, 665748170, 1996515036228, 22849956206052338, 978504298175393645420, 158156973836014224403041023, 96121270674841350006417715266220

Offset: 1

Author

R. H. Hardin Dec 16 2012

Keywords

• nonn

Comments

Diagonal of A220562

Examples

			Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
..0..6..4....0..7..7....0..6..4....6..4..7....6..4..0....0..7..7....0..7..7
..0..6..4....3..3..7....0..7..0....0..3..0....0..7..7....3..3..0....3..3..0
..0..6..4....0..3..0....3..0..0....0..0..0....3..3..0....0..0..0....6..4..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..18