A278054 Primes p of the form sigma(2^(q+1)) for some prime q.

31, 127, 8191, 524287, 2147483647, 2305843009213693951

Offset

1,1

Comments

The next term is too large to include (see the table).

Corresponding values of primes q are in A278053.

Subsequence of Mersenne primes (A000668).

Links

Jaroslav Krizek, Table of n, a(n) for n = 1..7

Example

8191 = sigma(2^(q+1)) for prime q = 11.

Mathematica

Select[DivisorSigma[1, 2^(# + 1)] & /@ Prime@ Range@ 120, PrimeQ] (* Michael De Vlieger, Nov 10 2016 *)

Prog

(Magma) [SumOfDivisors(2^(n+1)): n in [1..1000] | IsPrime(n) and IsPrime(SumOfDivisors(2^(n+1)))]

Crossrefs

Cf. A000043, A000203, A153798, A278053.

Sequence in context: A079141 A049203 A065403 * A035502 A259509 A183838

Adjacent sequences: A278051 A278052 A278053 * A278055 A278056 A278057

Keyword

nonn

Author

Jaroslav Krizek, Nov 09 2016

Status

approved