A113542 - OEIS

%I #10 Jun 13 2017 10:13:44

%S 18,20,37,56,58,96,113,134,151,172,227,229,246,265,267,286,305,322,

%T 341,362,398,400,474,476,493,495,590,609,626,645,647,664,683,685,740,

%U 780,799,835,894,911,932,968,970,987,1008,1025,1027,1044,1046,1063,1141

%N Numbers k such that (18*k^2+1)/19 is prime.

%H G. C. Greubel, <a href="/A113542/b113542.txt">Table of n, a(n) for n = 1..1000</a>

%t s={};Do[If[PrimeQ[(18n^2+1)/19], AppendTo[s, n]], {n, 2000}];s

%o (PARI) is(n)=isprime((18*n^2+1)/19) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Zak Seidov_, Jan 13 2006