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%I #15 Sep 08 2022 08:45:40
%S 1,2,3,7,8,9,10,12,14,17,19,22,24,29,33,35,42,43,50,52,57,58,65,68,72,
%T 73,75,77,94,99,105,107,117,119,120,124,129,138,140,143,155,162,178,
%U 184,187,189,190,194,199,204,208,210,219,220,229,245,248,250,252,254,255
%N Numbers k such that 5k^2-k+1 is prime.
%H Vincenzo Librandi, <a href="/A154432/b154432.txt">Table of n, a(n) for n = 1..1000</a>
%e The associated primes are p=5 for n=1, p=19 for n=2, p=43 for n=3, p=239 for n=7.
%p for n from 1 to 3000 do p := 5*n^2-n+1 ; if isprime(p) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Jan 12 2009
%t Select[Range[0, 300], PrimeQ[5*#^2 -# +1]&] (* _Vincenzo Librandi_, Sep 24 2012 *)
%o (Magma) [n: n in [0..300] | IsPrime(5*n^2 - n + 1)]; // _Vincenzo Librandi_, Sep 24 2012
%o (PARI) is(n)=isprime(5*n^2-n+1) \\ _Charles R Greathouse IV_, Sep 24 2012
%Y Cf. A154431.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Jan 09 2009
%E 114 removed; extended by _R. J. Mathar_, Jan 12 2009
%E Misleading formula removed by _R. J. Mathar_, Jul 24 2009
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