OFFSET
1,1
COMMENTS
Under Bunyakovsky's conjecture this sequence is infinite. - Charles R Greathouse IV, Dec 28 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
(25*25 + 3)/4 = 157, 157 is prime, 25 is the 7th term of the sequence.
MATHEMATICA
Select[Range[500], PrimeQ[(#^2 + 3)/4] &] (* Vincenzo Librandi, Oct 06 2012 *)
PROG
(PARI) for(k=2, 1e3, if(isprime(k^2+k+1), print1(2*k+1", "))) \\ Charles R Greathouse IV, Dec 28 2011
(Magma) [n: n in [1..400 by 2] | IsPrime((n^2 + 3) div 4)]; // Vincenzo Librandi, Oct 06 2012
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Pierre CAMI, Nov 13 2003
EXTENSIONS
Corrected and extended by Ray Chandler, Nov 16 2003
STATUS
approved