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Numbers n such that (140^n + 139^n)/279 is prime.
1

%I #12 Nov 27 2020 01:10:14

%S 23,41,43,151,2927,6133

%N Numbers n such that (140^n + 139^n)/279 is prime.

%C All terms are prime.

%C a(7) > 10^4.

%C a(7) > 43400. - _Lucas A. Brown_, Nov 26 2020

%o (PARI) is(n)=ispseudoprime((140^n+139^n)/279) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A000978, A057469, A128066, A128335, A128336, A187805, A181141, A187819, A217095.

%K hard,nonn,more

%O 1,1

%A _Jean-Louis Charton_, Jul 03 2013