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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
1, 5, 64, 3966, 810778, 665748170, 1996515036228, 22849956206052338, 978504298175393645420, 158156973836014224403041023, 96121270674841350006417715266220
OFFSET
1,2
COMMENTS
Diagonal of A220562
LINKS
EXAMPLE
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
CROSSREFS
Sequence in context: A061698 A351020 A238631 * A266962 A126955 A091105
KEYWORD
nonn
AUTHOR
R. H. Hardin Dec 16 2012
STATUS
approved