login
A177631
Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, up, down, down, up, up
0
1, 20, 1674, 363454, 161958230, 128735444262, 166178950132409, 325628012566801867
OFFSET
1,2
CROSSREFS
Sequence in context: A177627 A177620 A177632 * A177292 A266737 A177599
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved