A177572 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, down, down, down

1, 6, 90, 2502, 111060, 7197358, 641227980, 75188708366, 11226009350064, 2079447834540540

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177571 A177590 A177577 * A177583 A177578 A177582

Adjacent sequences: A177569 A177570 A177571 * A177573 A177574 A177575

Keyword

nonn

Author

R. H. Hardin May 10 2010

Status

approved