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a(n) is the least k such that k^n*(k^n+1)-1 is prime.
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%I #14 Sep 26 2019 08:02:19

%S 2,2,2,2,4,2,10,4,3,2,6,3,4,21,12,2,30,3,5,47,31,34,27,2,31,2,50,5,20,

%T 23,89,29,179,11,2,16,41,96,75,22,55,10,209,46,38,17,34,7,61,121,119,

%U 2,68,148,2,164,216,65,527,11,175,354,442,201,54,230,97,433,3

%N a(n) is the least k such that k^n*(k^n+1)-1 is prime.

%H Pierre CAMI, <a href="/A153436/b153436.txt">Table of n, a(n) for n = 1..500</a>

%o (PARI) a(n) = {my(k=1); while (! isprime(k^n*(k^n+1)-1), k++); k;}

%Y Cf. A101406, A153436, A153438.

%K nonn

%O 1,1

%A _Pierre CAMI_, Dec 26 2008

%E Name corrected by _Michel Marcus_, Sep 24 2019