A177587 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, up, down, up

1, 6, 90, 2436, 104872, 6591251, 568874050, 64561209403, 9324840163064, 1670314013465714

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177584 A177558 A177580 * A177585 A177559 A177581

Adjacent sequences: A177584 A177585 A177586 * A177588 A177589 A177590

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved