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A177572
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, down, down
0
1, 6, 90, 2502, 111060, 7197358, 641227980, 75188708366, 11226009350064, 2079447834540540
OFFSET
1,2
CROSSREFS
Sequence in context: A177571 A177590 A177577 * A177583 A177578 A177582
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved