%I
%S 3,23,41,47,53,59,107,131,137,173,179,191,251,263,293,311,443,467,503,
%T 599,641,971,977,1013,1049,1151,1277,1301,1307,1409,1427,1433,1451,
%U 1559,1607,1721,1913,1973,1979,2069,2111,2141,2267,2417,2693,2729,2777,2999
%N Primes p such that 1*p+20 and 20*p+1 are primes.
%t Select[Prime[Range[220]], PrimeQ[20#+1]&&PrimeQ[1#+20]&]
%o (Magma) [p: p in PrimesUpTo(10000) IsPrime(p+20) and IsPrime(20*p+1)] // _Vincenzo Librandi_, Nov 13 2010
%K nonn
%O 1,1
%A _Zak Seidov_, May 07 2005
%E More terms from _Vincenzo Librandi_, Apr 01 2010
