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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 0
1, 2, 22, 712, 127288, 94226589, 319803318494, 4830469921091502, 326643330141438534391 (list; graph; refs; listen; history; text; internal format)
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: A177042 A308535 A318639 * A333796 A132568 A279802

Adjacent sequences:  A220729 A220730 A220731 * A220733 A220734 A220735

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 18 2012

STATUS

approved

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Last modified July 29 17:41 EDT 2021. Contains 346346 sequences. (Running on oeis4.)