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A265121
Integers k such that k*3^k + 2 is prime.
1
0, 1, 3, 5, 11, 15, 17, 153, 169, 273, 317, 373, 923, 1403, 1969, 2349, 7809, 10313, 12291, 24865, 41289
OFFSET
1,3
COMMENTS
Initial corresponding primes are 2, 5, 83 and 1217.
How do this sequence and A006552 compare asymptotically?
a(22) > 10^5. - Michael S. Branicky, Oct 08 2024
EXAMPLE
a(3) = 3 because 3^3 * 3 + 2 = 83 is prime.
MATHEMATICA
Select[Range[0, 10000], PrimeQ[# 3^# + 2] &] (* Vincenzo Librandi, Dec 02 2015 *)
PROG
(PARI) for(n=0, 1e6, if(ispseudoprime(3^n*n + 2), print1(n, ", ")));
(Magma) [n: n in [0..400] | IsPrime(n*3^n+2)]; // Vincenzo Librandi, Dec 02 2015
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Altug Alkan, Dec 01 2015
EXTENSIONS
a(1) = 0 added by Vincenzo Librandi, Dec 02 2015
a(21) from Michael S. Branicky, May 16 2023
STATUS
approved