A172461 Primes p such that 2*p-1 and 2^p-1 are both primes.

2, 3, 7, 19, 31, 607, 1279, 2281, 44497, 1257787, 13466917

Offset

1,1

Links

Table of n, a(n) for n=1..11.

Example

a(1) = 2 is a term since it is a prime and 2^2 - 1 = 3 and 2*2 - 1 = 3 are primes.
a(2) = 3 is a term since it is a prime and 2^3 - 1 = 7 and 2*3 - 1 = 5 are primes.

Mathematica

Select[MersennePrimeExponent[Range[47]], PrimeQ[2# -1] &] (* Amiram Eldar, Jul 29 2020 *)

Crossrefs

Intersection of A000043 and A005382.

Cf. A000668.

Sequence in context: A152609 A298943 A340281 * A253971 A291339 A235616

Adjacent sequences: A172458 A172459 A172460 * A172462 A172463 A172464

Keyword

nonn,more

Author

Juri-Stepan Gerasimov, Feb 03 2010, Feb 06 2010

Extensions

a(9)-a(11) from Robert G. Wilson v, Feb 26 2010

Status

approved