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A177632
Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, up, down, up, down, down
0
1, 20, 1668, 359280, 158479620, 124510818960, 158686566550368, 306744815112615960
OFFSET
1,2
CROSSREFS
Sequence in context: A177622 A177627 A177620 * A177631 A177292 A266737
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved