A177593 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, up, up, down, down, down.

1, 6, 90, 2518, 113052, 7434180, 673334112, 80360724360, 12221802614520, 2307379944600182

Offset

1,2

Links

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

Crossrefs

Sequence in context: A177578 A177582 A177592 * A132467 A177284 A266735

Adjacent sequences: A177590 A177591 A177592 * A177594 A177595 A177596

Keyword

nonn,more,changed

Author

R. H. Hardin, May 10 2010

Status

approved