

A140521


Number of directed "king tours" on an n X n board.


4




OFFSET

1,2


COMMENTS

Or, number of directed Hamiltonian cycles in the graph P_n X P_n.
If the direction of the tour is not taken into account, the numbers for n > 1 must be halved (see A140519).
Computed using ZDDs (ZDD = "reduced, order, zerosuppressed binary decision diagram").


REFERENCES

D. E. Knuth, The Art of Computer Programming, Section 7.1.4, in preparation.


LINKS

Table of n, a(n) for n=1..8.
Eric Weisstein's World of Mathematics, Hamiltonian Cycle
Eric Weisstein's World of Mathematics, King Graph
Index entries for sequences related to graphs, Hamiltonian


CROSSREFS

Cf. A001230, A140519.
Sequence in context: A222605 A222749 A132548 * A171141 A069065 A073343
Adjacent sequences: A140518 A140519 A140520 * A140522 A140523 A140524


KEYWORD

nonn,walk


AUTHOR

Don Knuth, Jul 26 2008


STATUS

approved



