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

1,3

Comments

If it exists, a(12) > 30000.

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

Links

Table of n, a(n) for n=1..14.

Mathematica

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

Prog

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

Crossrefs

A052968, A187733.

Sequence in context: A261072 A154508 A073573 * A059621 A034926 A224849

Adjacent sequences: A309325 A309326 A309327 * A309329 A309330 A309331

Keyword

nonn,more,hard

Author

Hugo Pfoertner, Jul 23 2019

Extensions

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

Status

approved