A144054 Number of n X n binary arrays, symmetric under horizontal and vertical reflection, with every 1 adjacent to at least one other 1, but at most one 1 adjacent horizontally and at most one 1 adjacent vertically.

1, 2, 1, 5, 15, 65, 233, 1687, 8512, 96837, 990941, 16983353, 265775404, 7061955223, 183338740300, 7436406032400, 326859686075965, 20333610181788816, 1471382970077109810, 140578109521427255473, 16886941052098865528443

Offset

1,2

Links

Table of n, a(n) for n=1..21.

Crossrefs

Sequence in context: A268295 A063635 A192264 * A144058 A013014 A012905

Adjacent sequences: A144051 A144052 A144053 * A144055 A144056 A144057

Keyword

nonn

Author

R. H. Hardin, Sep 08 2008

Status

approved