OFFSET
1,1
COMMENTS
A subsequence of A112041.
MATHEMATICA
prQ[n_]:=Module[{ns=n*3^Range[0, 4]+1}, And@@PrimeQ[ns]]; Select[Range[ 810000], prQ] (* Harvey P. Dale, Jul 01 2012 *)
PROG
(Magma) [n: n in [1..1000000] |IsPrime(n+1) and IsPrime(3*n+1) and IsPrime(9*n+1) and IsPrime(27*n+1)and IsPrime(81*n+1)] // Vincenzo Librandi, Nov 13 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Aug 26 2005
STATUS
approved