OFFSET
1,2
COMMENTS
Equivalently, the number of partitionings of an n X n checkerboard into two edgewise-connected simply-connected sets. (Cf. A068416).
Each part is required to contain at least one cell and cuttings are considered different if they only differ by rotation or reflection.
MATHEMATICA
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 14 2016
STATUS
approved