OFFSET

1,4

COMMENTS

FORMULA

a(n) = A110218(n, n, n).

EXAMPLE

a(3) = 1, since up to rotations and reflections,

OOO KKK OOO

OKO OKO OKO

OOO OOO OOO is the only covering for n = 3.

CROSSREFS

KEYWORD

hard,more,nonn

AUTHOR

Nikolaus Meyberg (Nikolaus.Meyberg(AT)t-online.de), Jul 17 2005

STATUS

approved