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A177571
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, up, up
0
1, 6, 90, 2484, 109339, 7019168, 619051405, 71824824028, 10607707589930, 1943225496142169
OFFSET
1,2
CROSSREFS
Sequence in context: A177586 A177579 A177591 * A177590 A177577 A177572
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved