A087577 - OEIS

A087577

Smallest number k such that k^n + 3 is a prime.

2, 2, 2, 2, 8, 2, 2, 4, 4, 8, 10, 2, 20, 4, 2, 2, 10, 2, 124, 46, 16, 20, 190, 14, 68, 50, 152, 2, 34, 2, 34, 122, 130, 208, 374, 46, 68, 64, 10, 28, 248, 4, 106, 230, 34, 208, 52, 34, 154, 230, 116, 302, 656, 38, 2, 10, 16, 34, 140, 140, 20, 232, 140, 28, 64, 328, 2, 98, 28, 818

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

EXAMPLE

a(5) = 8 as 8^5 + 3= 32771 is prime, while 2^5 +3, 4^5+3 and 6^5 +3 are composite.

MATHEMATICA

snk[n_]:=Module[{k=1}, While[!PrimeQ[k^n+3], k++]; k]; Array[snk, 70] (* Harvey P. Dale, Mar 08 2014 *)

PROG

(PARI) for(j=1, 50, for (i=1, 150, if(isprime(i^j+3), print1(i, ", "); break())))

CROSSREFS