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

0, 6, 522, 178438

Offset

1,2

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.

Links

Table of n, a(n) for n=1..4.

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

Example

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

Mathematica

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

Prog

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

Crossrefs

Cf. A005574.

Sequence in context: A003395 A222607 A000411 * A202967 A230330 A252174

Adjacent sequences: A180428 A180429 A180430 * A180432 A180433 A180434

Keyword

nonn,more

Author

Serge Batalov, Sep 04 2010

Status

approved