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A220596 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops 0
1, 2, 65, 9047, 7558495, 41011388731, 1417058414112748, 305516864725171735943, 412489181606705015322075070 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Diagonal of A220602

LINKS

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

EXAMPLE

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

.00.00.00...00.78.78...68.46.47...68.46.48...00.67.48...00.78.00...00.67.47

.00.67.47...38.23.28...28.36.47...28.68.24...38.67.24...38.28.00...38.37.00

.36.34.00...26.46.24...26.34.00...26.24.00...23.00.00...26.24.00...23.00.00

CROSSREFS

Sequence in context: A185029 A228081 A214366 * A326253 A003821 A055765

Adjacent sequences:  A220593 A220594 A220595 * A220597 A220598 A220599

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 16 2012

STATUS

approved

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Last modified October 17 17:21 EDT 2021. Contains 348065 sequences. (Running on oeis4.)