A309328 - OEIS

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

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OFFSET

1,3

COMMENTS

If it exists, a(12) > 30000.

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

LINKS

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

KEYWORD

nonn,more,hard

AUTHOR

EXTENSIONS

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

STATUS

approved