OFFSET
1,1
COMMENTS
Or places of squares in A000430.
EXAMPLE
12 is in the sequence, since pi(23)+pi(sqrt(23))=9+2=11, while pi(29)+pi(sqrt(29))=10+3=13.
Also 12 is in the sequence since A000430(12)=25 is not prime.
MATHEMATICA
t = Table[PrimePi[n] + PrimePi[Sqrt[n]], {n, Prime[Range[10000]]}]; Complement[Range[t[[-1]]], t] (* T. D. Noe, Apr 09 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Apr 06 2012
STATUS
approved