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A220731 Number of ways to reciprocally link elements of an 7Xn array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors 0
1, 64, 9667, 3751888, 1208447287, 418227762771, 141539684300104, 48392485908572308 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 7 of A220725

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)

.69.47.00...00.00.00...69.49.00...00.67.47...69.49.00...00.69.47...00.00.00

.36.14.00...00.79.00...00.16.14...39.36.47...00.17.17...69.34.17...00.79.00

.69.47.00...36.46.14...69.46.47...00.13.00...36.34.00...00.13.00...36.49.17

.39.17.00...00.00.00...00.13.00...00.00.00...69.49.00...00.67.47...00.36.14

.36.14.00...00.00.00...00.79.00...00.79.00...00.17.17...39.37.00...00.79.00

.00.67.47...69.49.00...39.67.14...36.46.14...39.37.00...39.19.00...39.67.14

.36.34.00...00.16.14...36.14.00...00.00.00...36.14.00...00.16.14...36.14.00

CROSSREFS

Sequence in context: A222140 A093264 A264146 * A239403 A254607 A236690

Adjacent sequences:  A220728 A220729 A220730 * A220732 A220733 A220734

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 18 2012

STATUS

approved

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Last modified January 24 07:18 EST 2020. Contains 331189 sequences. (Running on oeis4.)