A180431 Numbers n such that 4*17^n+1 is prime.

0, 6, 522, 178438

Offset: 1

Author

Serge Batalov, Sep 04 2010

Keywords

• nonn
• more

Comments

For n>0, members of the sequence may only be of form 4k+2 (otherwise the expression is divisible by 3 or 5). Therefore members of the sequence are a subset of A005574 and are Generalized Fermat primes.

Examples

			For a(2) = 6 we have 4*17^6+1 = 96550277, which is prime.
		

Links

• Eric Weisstein's World of Mathematics, Generalized Fermat Number.

Crossrefs

Cf. A005574.

Programs

Mathematica

Do[ If[ PrimeQ[ 4*17^n+1], Print[ n ]], {n, 0, 10000}]

PARI

is(n)=isprime(4*17^n+1) \\ Charles R Greathouse IV, May 15 2013