A144239 Number of n X n binary arrays, symmetric about main diagonal, 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, 3, 9, 28, 108, 984, 7649, 73052, 1440611, 30613610, 770498233, 33712608974, 1836317274474, 122794791129401, 12495584324152671, 1697400189654813806

Offset

1,2

Links

Table of n, a(n) for n=1..17.

Crossrefs

Sequence in context: A099079 A339831 A006797 * A320951 A381339 A139006

Adjacent sequences: A144236 A144237 A144238 * A144240 A144241 A144242

Keyword

nonn

Author

R. H. Hardin, Sep 15 2008

Status

approved