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, zero-suppressed binary decision diagram").
REFERENCES
Donald E. Knuth, The Art of Computer Programming, Vol. 4, fascicle 1, section 7.1.4, p. 117, Addison-Wesley, 2009.
LINKS
Eric Weisstein's World of Mathematics, Hamiltonian Cycle
Eric Weisstein's World of Mathematics, King Graph
CROSSREFS
KEYWORD
nonn,walk
AUTHOR
Don Knuth, Jul 26 2008
STATUS
approved