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A330900 Number of terms of A066038 that do not exceed 10^n. 0
0, 2, 22, 130, 1196, 11698, 107315, 961924, 8641491, 78304633, 714962670, 6572968299 (list; graph; refs; listen; history; text; internal format)
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
Sequence in context: A292732 A206418 A255866 * A356341 A353191 A062180
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, May 01 2020
EXTENSIONS
a(11) from Giovanni Resta, May 05 2020
STATUS
approved

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Last modified March 28 07:48 EDT 2024. Contains 371235 sequences. (Running on oeis4.)