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A269544 Numbers n such that 7*8^n + 1 is prime. 2

%I

%S 2,40,58,60,130,144,752,7462,18162,69028,187272,268178,270410,497284,

%T 713304,722600,1005254

%N Numbers n such that 7*8^n + 1 is prime.

%C a(n) is even because 7*8^(2*k+1) + 1 is divisible by 3.

%F a(n) = A032353(n)/3 where this is an integer.

%t Select[Range[0, 200000,2], PrimeQ[7*8^# + 1] &]

%o (PARI) is(n)=ispseudoprime(7*8^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A056799, A245241, A268061.

%K nonn,hard,more

%O 1,1

%A _Robert Price_, Feb 29 2016

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Last modified December 8 01:46 EST 2019. Contains 329850 sequences. (Running on oeis4.)