A113480 Numbers n such that 17^n + 2 is prime.

0, 1, 105, 369, 25521

Offset

1,3

Comments

Only numbers of the form 6k-5 and 6k-3 need be tested.

No further terms < 100000. - Ray Chandler, Jul 31 2011

a(6) > 2*10^5. - Robert Price, Oct 23 2014

Links

Table of n, a(n) for n=1..5.

Henri & Renaud Lifchitz, PRP Records.

Mathematica

Do[If[PrimeQ[17^n + 2], Print[n]], {n, 0, 2500}] (* Stefan Steinerberger, Jan 28 2006 *)
Join[{0},
Select[Flatten[Table[6 n - {5, 3}, {n, 5000}]], PrimeQ[17^# + 2] &]] (* Harvey P. Dale, Feb 25 2021 *)

Prog

(PARI) g2(n)= { print1(0", "); forstep(x=1, n, 6, if(ispseudoprime(17^x+2), print1(x", ")); if(ispseudoprime(17^(x+2)+2), print1(x+2", ")) ) }

Crossrefs

Sequence in context: A147576 A145752 A195266 * A190577 A102792 A013594

Adjacent sequences: A113477 A113478 A113479 * A113481 A113482 A113483

Keyword

nonn

Author

Cino Hilliard, Jan 09 2006

Extensions

25521 from Ray Chandler, Jul 30 2011

Status

approved