A177583 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, down, down, down

1, 6, 90, 2504, 111312, 7228080, 645394636, 75850937208, 11351113909560, 2107488874630336

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177590 A177577 A177572 * A177578 A177582 A177592

Adjacent sequences: A177580 A177581 A177582 * A177584 A177585 A177586

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved