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A330900 Number of terms of A066038 that are not exceeding 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

Table of n, a(n) for n=0..11.

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

Cf. A006880, A008472, A066038, A073004.

Sequence in context: A292452 A292732 A255866 * A062180 A244719 A084399

Adjacent sequences:  A330897 A330898 A330899 * A330901 A330902 A330903

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 September 23 01:32 EDT 2020. Contains 337291 sequences. (Running on oeis4.)