A177579 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up, down, down

1, 6, 90, 2480, 109276, 7034376, 622234171, 72436184056, 10735917875964, 1973954128109493

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177581 A177566 A177586 * A177591 A177571 A177590

Adjacent sequences: A177576 A177577 A177578 * A177580 A177581 A177582

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved