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A127331 Primes p such that 6p-7 and 6p+7 are also primes. 1
2, 5, 11, 29, 31, 61, 71, 101, 109, 199, 229, 241, 269, 331, 379, 431, 491, 631, 691, 821, 919, 941, 991, 1049, 1061, 1259, 1289, 1321, 1409, 1439, 1451, 1459, 1571, 1621, 1831, 1861, 1931, 2039, 2089, 2161, 2251, 2281, 2311, 2389, 2399, 2441, 2539, 2551 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

31, 6*31-7=179, 6*31+7=193 are all primes.

MATHEMATICA

Select[Range[5000], PrimeQ[ # ] && PrimeQ[6# + 7] && PrimeQ[6# - 7] &]

Select[Prime[Range[3000]], PrimeQ[6 # - 7] && PrimeQ[6 # + 7]&] (* Vincenzo Librandi, Apr 09 2013 *)

PROG

(MAGMA) [p: p in PrimesUpTo(2600) | IsPrime(6*p-7) and IsPrime(6*p+7)]; // Vincenzo Librandi, Apr 09 2013

CROSSREFS

Sequence in context: A210517 A244531 A288390 * A040998 A215939 A309857

Adjacent sequences:  A127328 A127329 A127330 * A127332 A127333 A127334

KEYWORD

nonn,easy

AUTHOR

Zerinvary Lajos, Mar 30 2007

STATUS

approved

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Last modified January 29 08:12 EST 2020. Contains 331337 sequences. (Running on oeis4.)