A220630 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal or antidiagonal neighbors

1, 16, 158, 1665, 17527, 183961, 1932695, 20301254, 213251377, 2240062837, 23530357757, 247170637157, 2596361852466, 27273040848960, 286485012144200, 3009333012881404, 31611026051882958, 332052638832405598

Offset

1,2

Comments

Column 6 of A220632

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +31*a(n-2) +57*a(n-3) +43*a(n-4) -3*a(n-5) -36*a(n-6) +19*a(n-7) -6*a(n-8) +a(n-9)

Example

Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
.00.67.46.46.46.47...00.00.67.46.46.47...00.00.00.00.67.47...00.00.67.47.00.00
.36.46.47.00.37.00...00.36.46.47.37.00...00.00.00.36.34.00...00.37.37.67.46.47
.00.36.46.34.00.00...00.00.36.34.00.00...00.00.00.00.00.00...36.34.36.46.34.00

Crossrefs

Sequence in context: A211831 A036973 A101931 * A041005 A180798 A144453

Adjacent sequences: A220627 A220628 A220629 * A220631 A220632 A220633

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved