

A166852


Numbers n such that n^n + 3 is prime.


4




OFFSET

1,1


COMMENTS

Numbers corresponding to a(2) and a(3) are probable primes. 2770 is in the sequence so 2770^2770 + 3 is a probable prime; it is interesting that 277027703 is also prime. For the first term we have the same property: both 2^2 + 3 and 223 are prime.
The prime corresponding to the next term, if it exists, has more than 20000 digits.
For n = 1, n^n + 3 = 2 is prime but sequence focuses on the positive values of n.  Altug Alkan, Nov 28 2015


LINKS

Table of n, a(n) for n=1..3.


MATHEMATICA

Do[If[GCD[n, 3]==1&&PrimeQ[n^n+3], Print[n]], {n, 2, 5362, 2}]


PROG

(PARI) is(n)=ispseudoprime(n^n+3) \\ Charles R Greathouse IV, Jun 13 2017


CROSSREFS

Cf. A087037, A100407, A100408, A166853.
Sequence in context: A196292 A182447 A218437 * A236951 A111203 A159858
Adjacent sequences: A166849 A166850 A166851 * A166853 A166854 A166855


KEYWORD

hard,more,nonn,bref


AUTHOR

Farideh Firoozbakht, Nov 20 2009


STATUS

approved



