Permutations
Eric W. Weisstein
eww at wolfram.com
Wed Dec 17 04:38:29 CET 2003
On Mon, 15 Dec 2003, Christopher Tomaszewski wrote:
> I am currently attempting to derive a formula giving the total
> number of permutations of n elements such that no two elements which
> were consecutive in the original set are consecutive in any of the
> permutations.
>
> In order to easily remember the original positions of elements in
> empirical study, I simply use the set {1,2,3,...,n}.
>
> Here are all 24 permutations of {1,2,3,4}, with those satisfying my
> criteria in red:
There is no such thing as red in email...
> {1,2,3,4} {1,2,4,3} {1,3,2,4} {1,3,4,2} {1,4,2,3} {1,4,3,2}
> {2,1,3,4} {2,1,4,3} {2,3,1,4} {2,3,4,1} {2,4,1,3} {2,4,3,1} {3,1,2,4} {3,1,4,2} {3,2,1,4} {3,2,4,1} {3,4,1,2} {3,4,2,1}
> {4,1,2,3} {4,1,3,2} {4,2,1,3} {4,2,3,1} {4,3,1,2} {4,3,2,1}
If I understand your statement of the problem correctly:
http://www.research.att.com/projects/OEIS?Anum=A002464
Cheers,
-E
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