A002271 - OEIS

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

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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