A220732 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links

1, 2, 22, 712, 127288, 94226589, 319803318494, 4830469921091502, 326643330141438534391

Offset

1,2

Comments

Diagonal of A220738

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.00.67.47...00.69.47...00.69.47...00.69.47...00.67.47...00.00.00...00.79.00
.36.34.00...69.34.17...00.39.17...00.36.14...39.39.00...00.67.47...39.67.14
.00.00.00...00.13.00...00.36.14...00.00.00...00.16.14...36.34.00...36.14.00

Crossrefs

Sequence in context: A308535 A318639 A354243 * A333796 A132568 A279802

Adjacent sequences: A220729 A220730 A220731 * A220733 A220734 A220735

Keyword

nonn

Author

R. H. Hardin Dec 18 2012

Status

approved