A144244 Number of n X n binary arrays, symmetric under 180 degree rotation, with every 1 adjacent to at least one other 1 both bishopwise and rookwise but with no three 1s in a row bishopwise or rookwise.

1, 2, 1, 9, 24, 94, 870, 7731, 58940, 1518701, 25116276, 780979887, 31966477480

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Crossrefs

Sequence in context: A221756 A094633 A261060 * A079582 A259872 A320534

Adjacent sequences: A144241 A144242 A144243 * A144245 A144246 A144247

Keyword

nonn

Author

R. H. Hardin, Sep 15 2008

Status

approved