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A177587
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, up, down, up
0
1, 6, 90, 2436, 104872, 6591251, 568874050, 64561209403, 9324840163064, 1670314013465714
OFFSET
1,2
CROSSREFS
Sequence in context: A177584 A177558 A177580 * A177585 A177559 A177581
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved