login
A113900
Number of partitions of 2n X 2n checkerboard into two congruent edgewise-connected sets, counting partitions equal under rotation or reflection only once.
9
1, 6, 255, 92263, 281035054, 7490694495750, 1789509008288411290
OFFSET
1,2
REFERENCES
Howard Eves, A Survey of Geometry, 1963, p265.
EXAMPLE
All partitions are radially symmetric, hence can be identified by half the cut. The solution for 4 X 4 follows, with coordinates of starting point and direction of each subsequent incremental cut (North is positive Y).
(1,0)NNNES (1,0)NNE (1,0)NEN (1,0)NEENW (2,0)NN (2,0)NENW total = 6
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Joseph Sardinha (jsardi3(AT)juno.com), Jan 29 2006
EXTENSIONS
a(5) corrected by Giovanni Resta, May 14 2015
New value of a(5) confirmed by and additional values a(6) and a(7) from Andrew Howroyd, Apr 13 2016
STATUS
approved