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A112043 Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1, 81*k + 1, 243*k + 1 are all primes. 2
1171240, 1197630, 2023140, 3592890, 4132590, 4151910, 4254250, 4484760, 5167050, 5486110, 7121590, 7279930, 12524820, 13527640, 13595470, 15998640, 17211040, 17269000, 18570370, 20040300, 20402760, 21135310, 21735420 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..23.

MATHEMATICA

Select[Range[22*10^6], AllTrue[3^Range[0, 5] #+1, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 08 2019 *)

PROG

(MAGMA) [n: n in [1..50000000] |IsPrime(n+1) and IsPrime(3*n+1) and IsPrime(9*n+1) and IsPrime(27*n+1)and IsPrime(81*n+1)and IsPrime(243*n+1)] // Vincenzo Librandi, Nov 13 2010

CROSSREFS

Cf. A112041, A112042.

Sequence in context: A322690 A322680 A288077 * A114677 A172591 A250962

Adjacent sequences:  A112040 A112041 A112042 * A112044 A112045 A112046

KEYWORD

nonn

AUTHOR

Pierre CAMI, Aug 26 2005

STATUS

approved

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Last modified November 20 13:03 EST 2019. Contains 329336 sequences. (Running on oeis4.)