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A177585
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, down, up, up
0
1, 6, 90, 2446, 105516, 6624618, 570683441, 64611629712, 9304151482673, 1660908411640448
OFFSET
1,2
CROSSREFS
Sequence in context: A177558 A177580 A177587 * A177559 A177581 A177566
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved