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A220737 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links 1
1, 221, 10653, 824965, 60293428, 4335687696, 319803318494, 23223803317197, 1694411878011549, 123510214821475772, 9003987952938394208, 656405668520539476077, 47851358998828374751289, 3488414479767358266768461 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A220738

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..115

EXAMPLE

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

.00.67.49.00.00.79.00...00.79.79.79.00.00.00...00.67.47.00.00.00.00

.39.00.79.17.39.67.14...39.39.13.16.14.69.47...39.39.79.00.00.00.00

.00.13.36.14.36.14.00...00.16.14.00.00.36.14...00.13.16.14.00.00.00

CROSSREFS

Sequence in context: A020247 A177422 A177420 * A220723 A011816 A048902

Adjacent sequences:  A220734 A220735 A220736 * A220738 A220739 A220740

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 18 2012

STATUS

approved

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Last modified September 25 22:21 EDT 2020. Contains 337346 sequences. (Running on oeis4.)