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A177600
Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down.
0
1, 1, 20, 1680, 354624, 151213748, 114062310060, 139028830444866, 256400413791435360, 680598969845995094212, 2500271405904975564019712
OFFSET
0,3
CROSSREFS
Cf. A014606.
Sequence in context: A177292 A266737 A177599 * A177607 A177612 A177618
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 10 2010
EXTENSIONS
a(9)-a(10) from Alois P. Heinz, Nov 02 2013
STATUS
approved