A220686 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors

1, 351, 46027, 6349886, 822649205, 107713940118, 14108684022136, 1848014307847883, 242044667782801540, 31702119421997470360, 4152232349834304063419, 543844751860183504221026

Offset

1,2

Comments

Column 6 of A220688

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)
.00.67.46.46.46.48...00.00.68.48.00.00...00.67.46.46.46.48...68.46.47.68.46.48
.38.67.46.47.78.28...00.00.26.24.68.47...36.46.47.00.67.24...26.34.00.26.48.27
.23.00.36.34.26.24...00.00.00.00.23.00...00.36.46.34.00.00...00.00.00.00.23.00

Crossrefs

Sequence in context: A231707 A220333 A221294 * A167820 A145633 A252250

Adjacent sequences: A220683 A220684 A220685 * A220687 A220688 A220689

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved