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A213016 Numbers n such that the sum of prime factors of n (counted with multiplicity) is 3 times a prime. 1
8, 9, 14, 20, 24, 26, 27, 38, 44, 62, 68, 74, 105, 112, 116, 125, 126, 134, 150, 160, 180, 188, 192, 195, 208, 212, 216, 218, 231, 234, 243, 254, 275, 278, 314, 330, 332, 343, 352, 356, 362, 396, 398, 422, 428, 465, 483, 490, 496, 548, 558, 575, 588, 609, 614 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The numbers A100118(n)^3 are in the sequence.

LINKS

Table of n, a(n) for n=1..55.

FORMULA

sopfr(n) = 3*p, p prime.

EXAMPLE

44 is in the sequence because 44 = 2^2 * 11 => sum of prime factors = 2*2+11 = 15 = 3*5 where 5 is prime.

MAPLE

with(numtheory):A:= proc(n) local e, j; e := ifactors(n)[2]: add (e[j][1]*e[j][2], j=1..nops(e)) end: for m from 1 to 3000 do: if type(A(m)/3, prime)= true then printf(`%d, `, m):else fi:od:

MATHEMATICA

L = {}; Do[ww = Transpose[FactorInteger[k]]; w = ww[[1]].ww[[2]]; If[PrimeQ[w/3], AppendTo[L, k]], {k, 2, 1000}]; L

CROSSREFS

Cf. A001414, A100118, A213015.

Sequence in context: A096784 A175859 A059869 * A105833 A323249 A257037

Adjacent sequences:  A213013 A213014 A213015 * A213017 A213018 A213019

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jun 02 2012

STATUS

approved

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Last modified July 18 15:26 EDT 2019. Contains 325143 sequences. (Running on oeis4.)