Permutation of odds: Coprime Adjacents

[zak seidov]

If we "bend" permutation in circle, that is require
that the first and the last terms are also co-prime,
then we have:

1, 2, 6, 24, 60, 432, 3360, 6912, 86400,...

and i see that this is what Ray calls 
"Odd analog of A086595":

> Odd analog of A086595 = 1, 2, 6, 24, 60, 432, 3360,
> 6912, 86400, 1080000,...
ZakS
--- Ray Chandler <Ray.Chandler at comcast.net> wrote:

> This sequence is the "odd" analog of A076220 which
> is related to A086595 and A102381.
> 
> Odd analog of A076220 = 1, 2, 6, 24, 72, 480, 3600,
> 9600, 108000, 1270080,...
> 
> Odd analog of A086595 = 1, 2, 6, 24, 60, 432, 3360,
> 6912, 86400, 1080000,...
> 
> Odd analog of A102381 = 1, 1, 2, 6, 12, 72, 480,
> 864, 9600, 108000,...
> 
> I can find none of these sequences in the OEIS.
> 
> Ray Chandler
> 
> -----Original Message-----
> From: zak seidov [mailto:zakseidov at yahoo.com] 
> Sent: Friday, June 10, 2005 2:58 PM
> To: Leroy Quet
> Cc: seqfan at ext.jussieu.fr
> Subject: Re: Permutation of odds: Coprime Adjacents
> 
> 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]
> => 108000
> And for n from 1 to 9 we have (not in OEIS?) 1, 2,
> 6, 24, 72, 480, 3600, 9600,108000 For n=10 one needs
> more CP time ;=)
> Zak
> 
> 
> --- Leroy Quet <qq-quet at mindspring.com> wrote:
> 
> > Could someone please calculate/submit the sequence
> (or is it already 
> > in the OEIS?) where the nth term is the number of
> permutations of
> > (1,3,5,7,9,...,2n-1) where every adjacent pair in
> the permutations is 
> > coprime.
> > 
> > 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.
> > 
> > thanks,
> > Leroy Quet
> >  
> > 
> 
> 
> 
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