A177581 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up, up, down

1, 6, 90, 2466, 107556, 6834976, 596062132, 68333017226, 9966819746704, 1802533316442602

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177587 A177585 A177559 * A177566 A177586 A177579

Adjacent sequences: A177578 A177579 A177580 * A177582 A177583 A177584

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved