A113900 Number of partitions of 2n X 2n checkerboard into two congruent edgewise-connected sets, counting partitions equal under rotation or reflection only once.

1, 6, 255, 92263, 281035054, 7490694495750, 1789509008288411290

Offset: 1

Author

Joseph Sardinha (jsardi3(AT)juno.com), Jan 29 2006

Keywords

• nonn
• more

Examples

			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
		

References

• Howard Eves, A Survey of Geometry, 1963, p265.

Links

• Giovanni Resta, Illustrations for a(2) = 6 and a(3) = 255.

Crossrefs

Cf. A064941, A068392, A257952.

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