A169716 Numbers k such that 2^k - 127 is prime.

47, 55, 103, 143, 391, 2807, 11647, 19223, 264655

Offset: 1

Author

Zak Seidov, Apr 18 2010

Keywords

• nonn
• more

Comments

Exponents k arising in A175347: see that sequence for the actual primes.

The next term is > 10^4. [M. F. Hasler, Apr 18 2010]

All terms are == 7 (mod 8). [M. F. Hasler, Apr 18 2010]

No more terms through 78815. - Charles R Greathouse IV, Apr 19 2010

a(10) > 300000. - Michael S. Branicky, Jul 11 2025

Links

• Charles R Greathouse IV, Re: A175347: Primes in A176303, seqfan list, Apr 19 2010.

Crossrefs

Cf. A175347, A176303.

Programs

PARI

is(n)=ispseudoprime(2^n-127) \\ Charles R Greathouse IV, Sep 14 2015

Extensions

More terms from M. F. Hasler, Apr 18 2010

a(7)-a(8) from Charles R Greathouse IV, Apr 19 2010

a(9) from Michael S. Branicky, Jul 10 2025