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A178845
Number of permutations of 2..n+1 with no element divisible by an adjacent element.
0
1, 2, 2, 12, 20, 180, 648, 5784, 36936, 485040, 2034876, 33492048, 373375392, 4974252864, 52465459392, 1067273994240, 11538658531008, 260749481442240
OFFSET
1,2
CROSSREFS
Sequence in context: A302368 A346757 A202669 * A140431 A092900 A303537
KEYWORD
nonn
AUTHOR
R. H. Hardin Jun 17 2010
STATUS
approved