A220651 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two king-move neighbors, without 3-loops

1, 1441, 816159, 389859889, 179768901595, 85240331175084, 40274546959211319, 19024400007896312662, 8986807181301920000278, 4245342275704299946914591, 2005473806376394839453915403, 947373651435473076102298469864

Offset

1,2

Comments

Column 6 of A220652

Links

R. H. Hardin, Table of n, a(n) for n = 1..38

Example

Some solutions for n=3 0=self 1=nw 2=n 3=ne 4=w 6=e 7=sw 8=s 9=se (reciprocal directions total 10)
.00.67.46.48.69.47...00.00.00.78.68.48...00.69.46.49.69.47...00.00.78.00.79.00
.36.48.00.28.39.17...00.00.39.27.28.28...00.79.16.48.13.17...00.38.26.34.00.17
.00.26.46.24.36.14...00.00.36.14.26.24...36.46.14.26.34.00...00.26.46.46.34.00

Crossrefs

Sequence in context: A166609 A362863 A178275 * A252224 A221872 A251842

Adjacent sequences: A220648 A220649 A220650 * A220652 A220653 A220654

Keyword

nonn

Author

R. H. Hardin Dec 17 2012

Status

approved