A220742 Number of ways to reciprocally link elements of an 5 X n array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links.

1, 16, 258, 5760, 127288, 2792479, 60293428, 1311676964, 28429050419, 616803551956, 13375959455328, 290134376125496, 6292641300928077, 136484527133796904, 2960239399141332140, 64205688074746437957

Offset

1,2

Comments

Row 5 of A220738.

Links

R. H. Hardin, Table of n, a(n) for n = 1..209

Example

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.00.69.47...69.47.00...00.67.47...00.67.47...00.00.00...69.47.00...00.69.47
.00.36.14...39.16.47...39.36.47...36.34.00...00.00.00...39.16.47...69.34.17
.00.79.00...00.13.00...00.13.00...00.79.00...00.00.00...00.13.00...00.13.00
.39.00.17...69.49.00...00.67.47...36.47.17...00.69.47...00.00.00...00.67.47
.00.13.00...00.16.14...36.34.00...36.34.00...00.36.14...00.00.00...36.34.00

Crossrefs

Cf. A220738.

Sequence in context: A363689 A041482 A320362 * A266023 A223623 A264532

Adjacent sequences: A220739 A220740 A220741 * A220743 A220744 A220745

Keyword

nonn

Author

R. H. Hardin, Dec 18 2012

Status

approved