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A157341 Least number k such that 6*k^n-1 is prime, with k>1 when n>1. 2

%I #13 Sep 08 2022 08:45:41

%S 1,2,2,10,2,2,3,20,22,2,3,220,9,8,30,120,2,7,3,45,4,3,10,125,8,3,4,5,

%T 77,108,8,30,2,3,35,15,2,35,53,10,32,2,32,50,37,12,17,215,73,45,4,55,

%U 43,2,3,715,42,70,33,160,3,90,2,745,5,38,3,40,7,295,4,5,10,70,2,90,138,32,60

%N Least number k such that 6*k^n-1 is prime, with k>1 when n>1.

%H Marius A. Burtea, <a href="/A157341/b157341.txt">Table of n, a(n) for n = 1..230</a>

%o (PARI) a(n) = {my(k); if (n>1, k = 2, k = 1); while (!isprime(6*k^n-1), k++); k;} \\ _Michel Marcus_, Sep 15 2019

%o (Magma) sol:=[1]; for n in [2..80] do k:=2; while not IsPrime(6*k^n-1) do k:=k+1; end while; Append(~sol,k); end for; sol; // _Marius A. Burtea_, Sep 15 2019

%Y Cf. A164523 (where a(n)=2).

%K nonn

%O 1,2

%A _Pierre CAMI_, Feb 27 2009

%E Corrected by _Pierre CAMI_, Mar 09 2009

%E Name clarified by _Michel Marcus_, Sep 15 2019

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Last modified April 24 03:00 EDT 2024. Contains 371917 sequences. (Running on oeis4.)