OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..13
MATHEMATICA
s=""; For[i=1, i<5^2, If[PrimeQ[(i!+2)/2], s=s<>ToString[(i!+2)/2]<>", "]; i++ ]; Print[s] (* Vladimir Joseph Stephan Orlovsky, Apr 29 2008 *)
Select[Table[(n!+2)/2, {n, 0, 100}], PrimeQ] (* Vincenzo Librandi, Dec 07 2011 *)
PROG
(PARI) nfactp2d2(n) = { for(x=1, n, y=floor((x!+ 2)/2); if(isprime(y), print1(y", ")) ) }
(Magma) [ a: n in [1..50] | IsPrime(a) where a is (Factorial(n)+2) div 2 ];
CROSSREFS
KEYWORD
nonn
AUTHOR
Cino Hilliard, Dec 05 2003
STATUS
approved