login
A177567
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up, down
0
1, 6, 88, 2304, 95440, 5730914, 471168554, 50843909070, 6973120310921, 1184918837271686
OFFSET
1,2
CROSSREFS
Sequence in context: A122770 A265267 A218260 * A177563 A177569 A327645
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved