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A238817
Number of Hamiltonian cycles on 2n X 2n grid with at least 180-degree rotational symmetry.
0
1, 2, 28, 1504, 520176, 696179102, 5373177281748, 166903679914150336, 28636599794306124116062, 20262965974179958448766775754
OFFSET
1,2
LINKS
CROSSREFS
Cf. A003763.
Sequence in context: A063794 A361405 A331839 * A202942 A356518 A355070
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Mar 05 2014
STATUS
approved