A063791 -id:A063791 - cp's OEIS frontend

A099439 Numbers k such that A000295(k) = 2^k-k-1 is prime.

4, 10, 14, 16, 26, 50, 56, 70, 116, 2072, 6250, 13670, 14216, 14626, 396128

Offset: 1

Hugo Pfoertner, Oct 18 2004

The next term is > 400000.
Equals A063791 + 1. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008
Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

			a(1) = 4 because 2^4 - 4 - 1 = 11 is prime.

Cf. A000295 (2^n-n-1), A099440 (primes in A000295), A099441 (2^n-n-1 is a semiprime), A099442 (semiprimes in A000295).

a(15) (a PRP) from Karsten Bonath, Jun 07 2018

A296031 Numbers k such that 2^(k-1) - k is prime.

Original entry on oeis.org

5, 11, 15, 17, 27, 51, 57, 71, 117, 2073, 6251, 13671, 14217, 14627, 396128

Offset: 1

Thomas Gajdek, Dec 03 2017

a(15) > 200000. - Giovanni Resta, May 13 2018

			5 is in the sequence, because 2^4 - 5 = 11 is prime.

Cf. A063791, A099439.

Select[Range[6500], PrimeQ[2^(# - 1) - #] &] (* Michael De Vlieger, Apr 21 2018 *)

forstep(n=1, 10^6, 2, if(ispseudoprime(2^(n-1)-n),print1(n,", "))); \\ Joerg Arndt, Apr 15 2018

a(n) = A099439(n) + 1 = A063791(n) + 2.

Edited by Joerg Arndt, Apr 15 2018

a(15) from Michael S. Branicky, Apr 20 2025 using A099439

cp's OEIS Frontend

A099439 Numbers k such that A000295(k) = 2^k-k-1 is prime.

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A296031 Numbers k such that 2^(k-1) - k is prime.

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