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%I #25 Aug 02 2023 11:46:14
%S 1,2,4,7,8,12,15,28,31,84,98,128,238,302,859,1508,1586,2091,2796,2888,
%T 3924,4815,5636,6596,7090,20176,22176,56386,84050,115515,245608,
%U 259710,274120
%N Numbers n such that 7^n - 2 is a prime.
%e 7^12 - 2 = 13841287199 a prime number.
%t Do[ If[ PrimeQ[7^n - 2], Print[n]], {n, 1, 2000}] (* _Robert G. Wilson v_, Dec 22 2003 *)
%o (PARI) is(n)=isprime(7^n - 2) \\ _Charles R Greathouse IV_, Apr 28 2015
%Y Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.
%K nonn
%O 1,2
%A Herman H. Rosenfeld (herm3(AT)pacbell.net), Dec 16 2003
%E Corrected and extended by _Robert G. Wilson v_ and _Ray Chandler_, Dec 22 2003
%E Three more terms from _Ryan Propper_, Dec 07 2008
%E a(28)-a(30) from _Robert Price_, Jan 24 2014
%E a(31)-a(32) from _Paul Bourdelais_, Jan 29 2021
%E a(33) from _Paul Bourdelais_, Aug 02 2023
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