A177586 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, up, down, down

1, 6, 90, 2478, 108636, 6939540, 608630577, 70186000080, 10298227034520, 1873626436312246

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177559 A177581 A177566 * A177579 A177591 A177571

Adjacent sequences: A177583 A177584 A177585 * A177587 A177588 A177589

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved