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A309328
Numbers k such that 2^k + k + 2 is prime.
1
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
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
Hugo Pfoertner, Jul 23 2019
EXTENSIONS
a(12)-a(14) from Michael S. Branicky, Mar 26 2023
STATUS
approved