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A138697 Primes p such that 42*p-1, 42*p+1 and 48*p-1, 48*p+1 are twin primes. 6
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 (list; graph; refs; listen; history; text; internal format)
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: A182025 A221189 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

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Last modified January 24 13:52 EST 2020. Contains 331194 sequences. (Running on oeis4.)