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A213020 Smallest number k such that the sum of prime factors of k (counted with multiplicity) is n times a prime. 2
2, 4, 8, 15, 21, 35, 33, 39, 65, 51, 57, 95, 69, 115, 86, 87, 93, 155, 212, 111, 122, 123, 129, 215, 141, 235, 158, 159, 265, 371, 177, 183, 194, 427, 201, 335, 213, 219, 365, 511, 237, 395, 249, 415, 446, 267, 278, 623, 964, 291, 302, 303, 309, 515, 321, 327 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Smallest k such that sopfr(k) = n*p, p prime.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..5000

EXAMPLE

a(19) = 212 because 212 = 2^2 * 53 => sum of prime factors = 2*2+53 = 57 = 19*3 where 3 is prime.

MAPLE

sopfr:= proc(n) option remember;

          add(i[1]*i[2], i=ifactors(n)[2])

        end:

a:= proc(n) local k, p;

      for k from 2 while irem (sopfr(k), n, 'p')>0 or

        not isprime(p) do od; k

    end:

seq (a(n), n=1..100); # Alois P. Heinz, Jun 03 2012

CROSSREFS

Cf. A001414, A100118, A213015, A213016.

Sequence in context: A287163 A290652 A288313 * A279858 A026474 A301629

Adjacent sequences:  A213017 A213018 A213019 * A213021 A213022 A213023

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jun 02 2012

STATUS

approved

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Last modified July 19 08:33 EDT 2019. Contains 325155 sequences. (Running on oeis4.)