A177621 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, up, down, up.

1, 20, 1635, 339708, 143060850, 106681715484, 128573202886349, 234439539245241093

Offset

1,2

Links

Table of n, a(n) for n=1..8.

Crossrefs

Sequence in context: A331563 A250018 A177604 * A177628 A177626 A177609

Adjacent sequences: A177618 A177619 A177620 * A177622 A177623 A177624

Keyword

nonn

Author

R. H. Hardin, May 10 2010

Status

approved