login
A177583
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, down, down, down
0
1, 6, 90, 2504, 111312, 7228080, 645394636, 75850937208, 11351113909560, 2107488874630336
OFFSET
1,2
CROSSREFS
Sequence in context: A177590 A177577 A177572 * A177578 A177582 A177592
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved