OFFSET
1,2
COMMENTS
Odd analog of A076220.
EXAMPLE
For example, if n = 5, the permutation (5,3,7,9,1) is counted, but (5,3,9,1,7) is not counted because 3 and 9 are adjacent.
MATHEMATICA
With[{n=9}, per=Permutations[Range[1, 2 n -1, 2]]; Select[per, Times @@ Table[GCD @@Partition[ #, 2, 1][[i]], {i, n-1}]==1&]//Length] (Seidov)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ray Chandler, following a suggestion of Leroy Quet, Jun 11 2005
EXTENSIONS
a(1)-a(9) computed by Zak Seidov.
More terms from Max Alekseyev, Jun 11 2005
STATUS
approved