A171012 Number of ways to place two non-attacking wazirs on all free n-ominoes.

0, 0, 2, 14, 71, 341, 1591, 7610, 35432, 165209

Offset

1,3

Links

Table of n, a(n) for n=1..10.

Example

E.g. the triomino XXX admits 1 combination of 2 non-attacking wazirs.
The triomino XX admits 1 combination of 2 non-attacking wazirs.
............ X

Crossrefs

Sequence in context: A206947 A203241 A072888 * A094583 A002058 A095933

Adjacent sequences: A171009 A171010 A171011 * A171013 A171014 A171015

Keyword

nonn

Author

David Scambler, Aug 27 2010

Status

approved