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A090563 Numbers k such that 5*k^2 + 5*k + 1 is prime. 16

%I

%S 1,2,3,4,5,6,7,11,13,14,15,16,17,19,21,22,24,25,26,30,32,35,36,38,43,

%T 44,49,52,54,55,60,61,62,63,66,69,70,71,73,74,79,80,81,82,85,87,88,93,

%U 94,101,104,106,107,109,110,112,114,115,117,123,127,128,131,135

%N Numbers k such that 5*k^2 + 5*k + 1 is prime.

%t Do[s=5*n^2+5*n+1; If[PrimeQ[s], Print[n]], {n, 1, 1000}]

%o (PARI) isok(n) = isprime(5*n^2+5*n+1); \\ _Michel Marcus_, Apr 30 2016

%Y Cf. A090562.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Dec 11 2003

%E More terms from _Labos Elemer_, Dec 12 2003

%E Offset corrected by _Arkadiusz Wesolowski_, Aug 09 2011

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Last modified June 21 12:39 EDT 2021. Contains 345364 sequences. (Running on oeis4.)