OFFSET
0,2
COMMENTS
Luca & Moodley (2020) conjectured that a(n) ~ exp(gamma) * A006880(n).
LINKS
Florian Luca and Damon Moodley, Composite positive integers whose sum of prime factors is prime, Archivum Mathematicum, Vol. 56, No. 1 (2020), pp. 49-64.
EXAMPLE
There are 2 terms of A066038 not exceeding 10^1: 6 and 10. Thus a(1) = 2.
MATHEMATICA
b[1] = 0; b[n_] := Plus @@ FactorInteger[n][[;; , 1]]; bQ[n_] := PrimeNu[n] > 1 && PrimeQ[b[n]]; p = 1; s = 0; seq = {}; Do[If[bQ[n], s++]; If[n == p, p *= 10; AppendTo[seq, s]], {n, 1, 10^6}]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, May 01 2020
EXTENSIONS
a(11) from Giovanni Resta, May 05 2020
STATUS
approved