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A108134 Values of k such that k - 1 and k + 1 are twin primes and 3*k^9 - 1 and 3*k^9 + 1 are also twin primes. 1
4, 270, 37200, 57900, 63690, 80910, 150960, 256470, 367230, 405990, 577980, 641580, 706920, 1479480, 1547880, 1730580, 2026470, 2081160, 2210280, 2374530, 2423040, 2583240, 3090780, 3437220, 3510810, 4140420, 4441530, 4847460 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1000

EXAMPLE

270 is in the sequence because 270 - 1 = 269 and 270 + 1 = 271 are twin primes and 3*270^9 - 1 = 22876792454960999999999 and 3*270^9 + 1 = 22876792454961000000001 are also twin primes.

MATHEMATICA

fQ[n_] := Block[{p = n + 1}, PrimeQ[p + 1] && PrimeQ[3p^9 - 1] && PrimeQ[3p^9 + 1]]; Select[ Prime[ Range[408581]], fQ[ # ] &] + 1 (* Robert G. Wilson v, Jun 09 2005 *)

PROG

(MAGMA) twin:=func<p|IsPrime(p-1) and IsPrime(p+1)>; [k:k in [2..5000000]| twin(k) and twin(3*k^9)]; // Marius A. Burtea, Jan 03 2020

CROSSREFS

Sequence in context: A052136 A089667 A119008 * A221081 A340916 A000320

Adjacent sequences:  A108131 A108132 A108133 * A108135 A108136 A108137

KEYWORD

nonn

AUTHOR

Ray G. Opao, Jun 05 2005

EXTENSIONS

More terms from Robert G. Wilson v, Jun 09 2005

STATUS

approved

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Last modified October 19 09:36 EDT 2021. Contains 348074 sequences. (Running on oeis4.)