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A220631 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal or antidiagonal neighbors 1
1, 32, 564, 10695, 201903, 3817452, 72097810, 1362188752, 25734606523, 486186026515, 9185167500820, 173528846174065, 3278357276282501, 61935676290875214, 1170106754973419295, 22105996097313109325 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A220632

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 11*a(n-1) +119*a(n-2) +510*a(n-3) +1074*a(n-4) +735*a(n-5) -1120*a(n-6) -2716*a(n-7) +5687*a(n-8) -4250*a(n-9) +1973*a(n-10) -802*a(n-11) +244*a(n-12) -36*a(n-13) -4*a(n-14)

EXAMPLE

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

.00.00.00.00.00.67.47...00.67.47.67.47.67.47...00.67.46.47.00.67.47

.00.00.00.00.37.36.47...36.34.37.37.36.34.00...36.46.34.00.37.37.00

.00.00.00.36.46.34.00...00.36.34.00.00.00.00...00.00.00.36.34.00.00

CROSSREFS

Sequence in context: A178372 A082557 A022660 * A304308 A316207 A305774

Adjacent sequences:  A220628 A220629 A220630 * A220632 A220633 A220634

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 17 2012

STATUS

approved

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Last modified May 12 02:23 EDT 2021. Contains 343808 sequences. (Running on oeis4.)