A177617 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down, down, up.

1, 1, 20, 1680, 369600, 167510862, 135702841152, 178756061502340, 357729925926146006

Offset

0,3

Links

Table of n, a(n) for n=0..8.

Crossrefs

Cf. A014606.

Sequence in context: A266738 A177605 A177606 * A177629 A177630 A177294

Adjacent sequences: A177614 A177615 A177616 * A177618 A177619 A177620

Keyword

nonn

Author

R. H. Hardin, May 10 2010

Status

approved