A220744 Number of ways to reciprocally link elements of an 7 X n array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links.

1, 64, 3403, 355883, 32924133, 3287610473, 319803318494, 31411054258761, 3063698245151388

Offset

1,2

Comments

Row 7 of A220738.

Links

Table of n, a(n) for n=1..9.

Example

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.00.00.00...00.79.00...00.69.47...00.67.47...00.00.00...69.49.00...00.67.47
.00.00.00...39.69.14...00.36.14...39.39.00...00.67.47...00.17.17...36.34.00
.00.79.00...00.16.14...00.69.47...00.17.17...36.34.00...36.34.00...00.00.00
.39.79.17...69.47.00...00.36.14...36.34.00...69.49.00...69.47.00...00.69.47
.39.13.17...36.14.00...00.79.00...69.47.00...69.14.17...36.14.00...00.36.14
.00.13.00...69.47.00...39.69.14...39.17.00...00.13.00...69.47.00...00.00.00
.00.00.00...36.14.00...00.16.14...36.14.00...00.00.00...36.14.00...00.00.00

Crossrefs

Cf. A220738.

Sequence in context: A299179 A299941 A017439 * A298194 A299088 A299344

Adjacent sequences: A220741 A220742 A220743 * A220745 A220746 A220747

Keyword

nonn

Author

R. H. Hardin, Dec 18 2012

Status

approved