A106066 Primes p such that 1*p+20 and 20*p+1 are primes.

3, 23, 41, 47, 53, 59, 107, 131, 137, 173, 179, 191, 251, 263, 293, 311, 443, 467, 503, 599, 641, 971, 977, 1013, 1049, 1151, 1277, 1301, 1307, 1409, 1427, 1433, 1451, 1559, 1607, 1721, 1913, 1973, 1979, 2069, 2111, 2141, 2267, 2417, 2693, 2729, 2777, 2999

Offset: 1

Author

Zak Seidov, May 07 2005

Keywords

• nonn

Programs

Magma

[p: p in PrimesUpTo(10000)| IsPrime(p+20) and IsPrime(20*p+1)] // Vincenzo Librandi, Nov 13 2010

Mathematica

Select[Prime[Range[220]], PrimeQ[20#+1]&&PrimeQ[1#+20]&]

Extensions

More terms from Vincenzo Librandi, Apr 01 2010