A229165 a(n) is the number of n X n matrices of 0's, 1's and -1's in which the entries in each row or column sum to 1 and there are no adjacent -1's or 1's in any row or column.

1, 2, 7, 104, 7255, 2280064, 2708080414, 13039886441460

Offset

1,2

Links

Table of n, a(n) for n=1..8.

Crossrefs

Cf. A005130 (Robbins numbers).

Cf. A050204 (entries in each row or column sum to 1).

Sequence in context: A206157 A102747 A122524 * A307329 A162634 A235470

Adjacent sequences: A229162 A229163 A229164 * A229166 A229167 A229168

Keyword

nonn,more

Author

Eric W. Weisstein, Sep 25 2013

Extensions

Additional terms from R. H. Hardin, Sep 25 2013

Status

approved