OFFSET
1,1
COMMENTS
All these primes are sums of two squares, also all indices are sums of two squares since we have the identity 64k+21 = 4(4(4k+1)+1)+1.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
a = {}; Do[If[PrimeQ[21 + 64 n], AppendTo[a, 21 + 64 n]], {n, 0, 200}]; a
Select[Prime[Range[1700]], MemberQ[{21}, Mod[#, 64]] &] (* Vincenzo Librandi, Sep 06 2012 *)
PROG
(Magma) [p: p in PrimesUpTo(11000) | p mod 64 eq 21 ]; // Vincenzo Librandi, Sep 06 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Jan 19 2007, Nov 12 2007
STATUS
approved