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%I #10 Jun 13 2017 13:48:04
%S 1,9,33,69,427,1009,2667
%N Numbers n such that 4*17^n - 1 is prime.
%t Table[If[PrimeQ[4*17^n-1],Print[n];n],{n,1,20000}]
%o (PARI) is(n)=ispseudoprime(4*17^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A180431 (numbers n such that 4*17^n + 1 is prime).
%Y Cf. A205521 (numbers n such that 4*11^n - 1 is prime).
%Y Cf. A046865 (numbers n such that 4*5^n - 1 is prime).
%Y Cf. A005540 (numbers n such that 4*3^n - 1 is prime).
%K nonn
%O 1,2
%A _José María Grau Ribas_, Jan 31 2012
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