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 A217082 Numbers n such that (n^61-1)/(n-1) is prime. 6

%I

%S 2,19,69,88,138,155,205,234,336,420,425,455,470,525,555,561,608,626,

%T 667,674,766,779,846,851,937,971,998,1053,1055,1112,1137,1263,1329,

%U 1383,1445,1448,1499,1544,1551,1578,1640,1689,1724,1750,1793,1868,2143,2241,2358

%N Numbers n such that (n^61-1)/(n-1) is prime.

%H Vincenzo Librandi, <a href="/A217082/b217082.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[2, 2400], PrimeQ[(#^61 - 1)/(# - 1)] &] (* _T. D. Noe_, Sep 26 2012 *)

%o (MAGMA) [n: n in [2..2400] |IsPrime((n^61 - 1) div (n - 1))]; // _Vincenzo Librandi_, Sep 28 2012

%o (PARI) is(n)=isprime((n^61-1)/(n-1)) \\ _Charles R Greathouse IV_, Feb 17 2017

%Y Cf. A002384, A049409, A100330, A162862, A217070-A217089.

%K nonn,easy

%O 1,1

%A _Tim Johannes Ohrtmann_, Sep 26 2012

%E More terms from _T. D. Noe_, Sep 26 2012

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Last modified January 23 07:07 EST 2020. Contains 331168 sequences. (Running on oeis4.)