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A177603
Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, up, up
0
1, 20, 1506, 281943, 105629113, 69583938263, 73781411431903, 118056997361635333
OFFSET
1,2
CROSSREFS
Sequence in context: A193309 A177601 A200900 * A160308 A177625 A203481
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved