OFFSET
1,1
COMMENTS
Subsequence of A002327. - Charles R Greathouse IV, Aug 11 2009
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..3000
EXAMPLE
((3+1)/2)^2+((3-1)/2) = 4+1 = 5;
((5+1)/2)^2+((5-1)/2) = 9+2 = 11;
((7+1)/2)^2+((7-1)/2) = 16+3 = 19.
MATHEMATICA
f[n_]:=((p+1)/2)^2+((p-1)/2); lst={}; Do[p=Prime[n]; If[PrimeQ[f[p]], AppendTo[lst, f[p]]], {n, 6!}]; lst
Select[((#+1)/2)^2+(#-1)/2&/@Prime[Range[500]], PrimeQ] (* Harvey P. Dale, Nov 25 2012 *)
PROG
(Magma) [a: p in PrimesInInterval(3, 600) | IsPrime(a) where a is (p^2 + 4*p - 1) div 4]; // Vincenzo Librandi, Sep 17 2016
(PARI) lista(nn) = forprime(p=3, nn, if(isprime(P=(p^2+4*p-1)/4), print1(P, ", "))); \\ Altug Alkan, Sep 17 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jul 27 2009
STATUS
approved