A220552 Number of ways to reciprocally link elements of an n X 7 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor.

21, 5536, 940432, 174911750, 32001129185, 5873481159019, 1077372801893440, 197644957649145164, 36257360400073221806, 6651328207323063530996, 1220169722761405665767328, 223837152224277574339972896

Offset

1,1

Comments

Column 7 of A220553.

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
..0..7..7..7..0..0..0....0..7..8..8..0..6..4....0..7..7..6..4..6..4
..3..3..3..7..7..7..0....3..0..2..2..0..0..7....3..3..7..0..6..4..0
..0..0..3..3..3..0..0....0..6..4..0..0..3..0....0..3..0..0..6..4..0

Crossrefs

Cf. A220553.

Sequence in context: A203370 A232344 A074053 * A275053 A028451 A178327

Adjacent sequences: A220549 A220550 A220551 * A220553 A220554 A220555

Keyword

nonn

Author

R. H. Hardin, Dec 15 2012

Status

approved