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Numbers m such that 11^m + 6 is prime.
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%I #44 Mar 03 2021 09:18:54

%S 0,1,2,25,26,70,130,784,818,895,7843,41294,114458,160663,281143

%N Numbers m such that 11^m + 6 is prime.

%C a(12) > 35000, if it exists. - _Giovanni Resta_, Aug 10 2018

%C For m = 3*k, (11^m + 6)/7 is an integer, so there are no multiples of 3 in this sequence.

%C After a(2), there are no terms congruent to 1 mod 16, because 11^(16*k+1) + 6 is divisible by 17. - _Bruno Berselli_, Sep 20 2018

%e 11^2 + 6 = 127 is prime, hence 2 is a term.

%t Select[Range[0, 5000], PrimeQ[11^# + 6] &]

%o (PARI) for(n=0, 5000, if(ispseudoprime(11^n+6), print1(n, ", ")))

%Y Cf. A109076.

%K nonn,more

%O 1,3

%A _Jinyuan Wang_, Aug 09 2018

%E a(11) from _Giovanni Resta_, Aug 10 2018

%E a(12) from Lelio R Paula, Oct 2012

%E a(13)-a(14) from _Paul Bourdelais_, Feb 26 2021

%E a(15) from _Paul Bourdelais_, Mar 03 2021