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A220636 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors 1
1, 1, 13, 351, 8560, 183961, 3817452, 79063898, 1643423543, 34184820039, 711142299027, 14793696906106, 307746212613995, 6401868705356519, 133174202661890384, 2770341001987547086, 57629691849567578540 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Row 6 of A220632

LINKS

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

FORMULA

Empirical: a(n) = 32*a(n-1) -195*a(n-2) -1350*a(n-3) +10665*a(n-4) +31692*a(n-5) -206199*a(n-6) -507142*a(n-7) +1799954*a(n-8) +4606048*a(n-9) -7358332*a(n-10) -21711948*a(n-11) +13920815*a(n-12) +54513592*a(n-13) -9084809*a(n-14) -73913886*a(n-15) -4653883*a(n-16) +53601160*a(n-17) +7698097*a(n-18) -21029870*a(n-19) -3072503*a(n-20) +4411176*a(n-21) +533603*a(n-22) -476894*a(n-23) -41967*a(n-24) +24240*a(n-25) +1155*a(n-26) -450*a(n-27) for n>32

EXAMPLE

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

.00.67.47...00.67.47...00.67.47...00.00.00...00.00.00...00.00.00...00.67.47

.36.34.00...36.34.00...36.34.00...00.67.47...00.00.00...00.00.00...36.34.00

.00.00.00...00.67.47...00.00.00...36.34.00...00.67.47...00.67.47...00.00.00

.00.00.00...36.34.00...00.00.00...00.00.00...36.34.00...36.34.00...00.67.47

.00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00...36.34.00

.36.34.00...00.00.00...00.00.00...00.00.00...36.34.00...00.00.00...00.00.00

CROSSREFS

Sequence in context: A160396 A253125 A297070 * A078738 A218419 A165391

Adjacent sequences:  A220633 A220634 A220635 * A220637 A220638 A220639

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 17 2012

STATUS

approved

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Last modified May 17 19:36 EDT 2021. Contains 343988 sequences. (Running on oeis4.)