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A075714 1+n+n^s is a prime, s=18.

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%I A075714 #16 Sep 08 2022 08:45:07
%S A075714 1,2,9,24,27,44,80,251,263,311,332,356,366,371,458,515,546,548,561,
%T A075714 566,597,599,608,650,674,713,717,722,746,762,855,867,909,969,989,993,
%U A075714 1010,1011,1022,1052,1064,1191,1245,1269,1275,1284,1355,1376,1431,1473
%N A075714 1+n+n^s is a prime, s=18.
%C A075714 For s = 5,8,11,14,17,20,..., n_s=1+n+n^s is always composite for any n>1. Also at n=1, n_s=3 is a prime for any s. So it is interesting to consider only the cases of s =/= 5,8,11,14,17,20,... and n>1. Here i consider the case s=18 and find several first n's making n_s a prime (or a probable prime).
%H A075714 Vincenzo Librandi, <a href="/A075714/b075714.txt">Table of n, a(n) for n = 1..1500</a>
%e A075714 2 is OK because at s=18, n=2, n_s=1+n+n^s=262147 is a prime.
%t A075714 Select[Range[1800], PrimeQ[1 + # + #^18] &]  (* _Harvey P. Dale_, Mar 24 2011 *)
%o A075714 (PARI) for(n=1,1000,if(isprime(1+n+n^18),print1(n",")))
%o A075714 (Magma) [n: n in [0..1600] | IsPrime(s) where s is 1+n+n^18]; // _Vincenzo Librandi_, Jul 28 2014
%Y A075714 Cf. A002384, A075713, A075715.
%K A075714 nonn,easy
%O A075714 1,2
%A A075714 _Zak Seidov_, Oct 03 2002
%E A075714 More terms from _Ralf Stephan_, Apr 05 2003