OFFSET
1,1
COMMENTS
Subset of the primes (A000040).
Except for 5 and 7, if one member of a twin prime pair is included, the other is not.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
phi2[n_] := phi2[n] = Count[Range[n-1], _?(Total[Last /@ FactorInteger[#]] == 2 && CoprimeQ[#, n] &)];
Select[Range[300], And @@ Table[phi2[#] > phi2[k], {k, #-1}] &]
(* Andrey Zabolotskiy, Sep 09 2019 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Reikku Kulon, Sep 20 2008
STATUS
approved