A177601 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, up.

1, 20, 1477, 263978, 93489715, 57920130894, 57577729726875, 86198179666698834, 185132216218421052414, 548986840452318863546904

Offset

1,2

Links

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

Crossrefs

Sequence in context: A127847 A363512 A193309 * A200900 A177603 A160308

Adjacent sequences: A177598 A177599 A177600 * A177602 A177603 A177604

Keyword

nonn

Author

R. H. Hardin, May 10 2010

Extensions

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

Status

approved