login
A171009
Number of ways to place two non-attacking queens on all free n-ominoes.
0
0, 0, 0, 2, 21, 131, 733, 3882, 19641, 97282
OFFSET
1,4
EXAMPLE
The pentomino XXXX admits 2 combinations of 2 non-attacking queens.
............. X
CROSSREFS
Sequence in context: A091789 A109789 A136588 * A098661 A095262 A209519
KEYWORD
nonn
AUTHOR
David Scambler, Aug 27 2010
STATUS
approved