A309328 Numbers k such that 2^k + k + 2 is prime.

0, 1, 3, 7, 9, 19, 27, 33, 147, 639, 12243, 41427, 44287, 44449

Offset: 1

Author

Hugo Pfoertner, Jul 23 2019

Keywords

• nonn
• more
• hard

Comments

If it exists, a(12) > 30000.

a(15) > 100000. - Michael S. Branicky, Mar 27 2023

Crossrefs

A052968, A187733.

Programs

Mathematica

Select[Range[0, 2047], PrimeQ[2^# + # + 2] &] (* Alonso del Arte, Jul 23 2019 *)

PARI

for(n=0,15000,my(x=2^n+n+2); if(ispseudoprime(x), print1(n,", ")))

Extensions

a(12)-a(14) from Michael S. Branicky, Mar 26 2023