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A177634
Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, up, up, down, down, down
0
1, 20, 1680, 369240, 167472864, 135960447600, 179637314905576, 360796550854271920
OFFSET
1,2
CROSSREFS
Sequence in context: A177619 A177623 A177633 * A177293 A266738 A177605
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved