OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
247 is a term because 247 = 13*19, 2*247 - 1 = 493 = 17*29, 4*247 - 3 = 985 = 5*197, 8*247 - 1 = 1969 = 11*179, and 16*247 - 15 = 3937 = 31*127.
MATHEMATICA
f[n_]:=Last/@FactorInteger[n]=={1, 1}; lst={}; Do[If[f[n]&&f[2*n-1]&&f[4*n-3]&&f[8*n-7]&&f[16*n-15], AppendTo[lst, n]], {n, 0, 8!}]; lst
ptdpQ[n_]:=PrimeNu[n]==PrimeOmega[n]==2; Select[Range[11000], AllTrue[ {#, 2#-1, 4#-3, 8#-7, 16#-15}, ptdpQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 30 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, May 04 2010
STATUS
approved