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


%S 0,6,522,178438

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

%C 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.

%H <a href="http://mathworld.wolfram.com/GeneralizedFermatNumber.html">Generalized Fermat number at MathWorld</a>

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

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

%o (PARI) is(n)=isprime(4*17^n+1) \\ _Charles R Greathouse IV_, May 15 2013

%K more,nonn

%O 1,2

%A _Serge Batalov_, Sep 04 2010

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Last modified July 5 03:05 EDT 2020. Contains 335457 sequences. (Running on oeis4.)