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A177591
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, up, down, down
0
1, 6, 90, 2482, 109476, 7045740, 623113066, 72495993816, 10736006696280, 1971973147757382
OFFSET
1,2
CROSSREFS
Sequence in context: A177566 A177586 A177579 * A177571 A177590 A177577
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved