A210997 Number of free polyominoes with 2n-1 cells.

1, 2, 12, 108, 1285, 17073, 238591, 3426576, 50107909, 742624232, 11123060678, 168047007728, 2557227044764, 39153010938487, 602621953061978, 9317706529987950, 144648268175306702, 2253491528465905342, 35218318816847951974

Offset: 1

Author

Omar E. Pol, Sep 15 2012

Keywords

• nonn

Links

• John Mason, Table of n, a(n) for n = 1..25
• Eric Weisstein's World of Mathematics, Polyomino
• Wikipedia, Polyomino

Crossrefs

Bisection of A000105.

Cf. A000988, A210989, A210996.