OFFSET
1,1
COMMENTS
of three successive applications of the substitution p->(p-1)/2, and remain prime after each
three successive applications of the substitution p->2p+1. Therefore the sequence is a subsequence
of A162019.
They appear for example in the middle of chains started in A059767 or in even longer Cunningham chains. [R. J. Mathar, Jun 26 2009].
MATHEMATICA
f[n_]:=Module[{x}, If[PrimeQ[(n-1)/2]&&PrimeQ[(((n-1)/2)-1)/2]&&PrimeQ[(((((n-1)/ 2)-1)/2)-1)/2]&&PrimeQ[2*n+1]&&PrimeQ[2*(2*n+1)+1]&&PrimeQ[2*(2*(2*n+1)+1)+1], x=1, x=0]; x]; lst={}; Do[p=Prime[n]; If[f[p]!=0, AppendTo[lst, p]], {n, 6*10!}]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jun 25 2009
EXTENSIONS
Edited by R. J. Mathar, Jun 26 2009
STATUS
approved