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.

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

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: A089667 A119008 A357559 * 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