A002271 Numbers m such that all odd numbers k, 1 < k < m, relatively prime to m are primes.

2, 3, 4, 5, 6, 7, 8, 9, 12, 15, 18, 21, 24, 30, 45, 105

Offset

1,1

Comments

Joe Roberts writes that it is an assertion of Cseh that 105 is the last term. This sequence appears to be the same as A141109/2. - T. D. Noe, Jun 03 2008

References

J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 219.

L. Cseh, Generalized integers and Bonse's theorem, Studia Univ. Babes-Bolyai Math. 34 (1989), 3-6.

Links

Table of n, a(n) for n=1..16.

Example

15 is in this sequence because the odd numbers in [3,13] relatively prime to 15 are 7, 11 and 13, which are all prime.

Crossrefs

Sequence in context: A261874 A334929 A008816 * A048381 A185186 A336580

Adjacent sequences: A002268 A002269 A002270 * A002272 A002273 A002274

Keyword

nonn,fini,full

Author

N. J. A. Sloane

Status

approved