A161758 a(n)=n-p+1 where p is the maximal prime less than n-2.

4, 4, 5, 4, 5, 4, 5, 6, 7, 4, 5, 4, 5, 6, 7, 4, 5, 4, 5, 6, 7, 4, 5, 6, 7, 8, 9, 4, 5, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 4, 5, 4, 5, 6, 7, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 8, 9, 4, 5, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 4, 5, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 8, 9, 10, 11, 4

Offset

5,1

Comments

By a theorem of Jordan from 1873, a permutation group of degree n is alternating or symmetric if it is a(n)-transitive. For example, a permutation group of degree 100 is alternating or symmetric if it is 4-transitive, since a(100)=100-97+1=4.

References

Camille Jordan, Oeuvres, Volume I, 57.

Links

Table of n, a(n) for n=5..100.

Prog

(PARI) a(n) = n - precprime(n-3) + 1 \\ Michel Marcus, Jun 16 2013

Crossrefs

Sequence in context: A016709 A023403 A091283 * A046566 A046593 A158935

Adjacent sequences: A161755 A161756 A161757 * A161759 A161760 A161761

Keyword

nonn

Author

David Brink, Jun 18 2009

Status

approved