OFFSET
1,1
COMMENTS
This is a subsequence of A237658.
Conjecture: The sequence has infinitely many terms.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000 (n = 1..600 from Zhi-Wei Sun)
EXAMPLE
a(1) = 17 with pi(17) = 7 and pi(17^2) = 61 both prime.
a(2) = 41 with pi(41) = 13 and pi(41^2) = 263 both prime.
MATHEMATICA
p[m_]:=PrimeQ[PrimePi[m^2]]
n=0; Do[If[p[Prime[Prime[k]]], n=n+1; Print[n, " ", Prime[Prime[k]]]], {k, 1, 1000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Feb 11 2014
STATUS
approved