A138697 Primes p such that 42*p-1, 42*p+1 and 48*p-1, 48*p+1 are twin primes.

31, 331, 2971, 4421, 4861, 5309, 5441, 20431, 22381, 23459, 28151, 33911, 37061, 37699, 47491, 66449, 75821, 82799, 83701, 86131, 91961, 106621, 110059, 112289, 130811, 134669, 135461, 141601, 144461, 152959, 153701, 167311, 167759, 171049

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..2000

Example

42*31-1=1301, 42*31+1=1303; 48*31-1=1487, 48*31+1=1489; ...

Mathematica

a=42; b=48; Select[Prime[Range[14^4]], PrimeQ[a*#-1]&&PrimeQ[a*#+1]&&PrimeQ[b*#-1]&&PrimeQ[b*#+1]&]

Prog

(Magma) [p: p in PrimesUpTo(1000)| IsPrime(42*p-1) and IsPrime(42*p+1) and IsPrime(48*p-1) and IsPrime(48*p+1)]; // Vincenzo Librandi, Nov 24 2010

Crossrefs

Sequence in context: A221189 A362493 A029813 * A186071 A033175 A123568

Adjacent sequences: A138694 A138695 A138696 * A138698 A138699 A138700

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, May 15 2008

Extensions

More terms from Vincenzo Librandi, Apr 01 2010

Status

approved