A177597 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down.

1, 20, 1338, 209079, 63406701, 33142617807, 27492398898930, 34056987326957589, 60130947572363390910, 145825864087539572389710

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Crossrefs

Sequence in context: A274645 A005982 A229476 * A127847 A363512 A193309

Adjacent sequences: A177594 A177595 A177596 * A177598 A177599 A177600

Keyword

nonn

Author

R. H. Hardin, May 10 2010

Extensions

a(9)-a(10) from Alois P. Heinz, Nov 02 2013

Status

approved