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A106066 Primes p such that 1*p+20 and 20*p+1 are primes. 2

%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

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Last modified September 25 17:49 EDT 2022. Contains 356986 sequences. (Running on oeis4.)