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A177590
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, down, up, up
0
1, 6, 90, 2496, 110760, 7183476, 640668497, 75212295268, 11244165636152, 2085704995841392
OFFSET
1,2
CROSSREFS
Sequence in context: A177579 A177591 A177571 * A177577 A177572 A177583
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved