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A131564 Let spm(n) be the sum of all prime factors of n counted with multiplicities (A001414); sequence gives numbers n such that spm(n+spm(n)) divides both n and n+spm(n). 0
60, 70, 240, 2079, 2408, 2928, 3000, 3125, 4250, 6748, 15560, 19018, 19805, 22448, 24508, 28560, 29412, 31416, 33160, 39347, 43868, 44268, 46025, 53928, 55298, 70438, 78387, 80236, 81655, 91238, 94800, 96824, 106134, 117952 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..34.

EXAMPLE

Take 60, having sum of prime factors 2+2+3+5=12 and add that 12 to 60 to get 72, having the sum of its prime factors 2+2+2+3+3=12. We see that this 12 divides both 60 and 72.

For 2408, the sum of prime factors is 2+2+2+7+43=56, added to 2408 gives 2464, with sum of prime factors being 2+2+2+2+2+7+11=28; this 28 divides both 2408 and 2464.

CROSSREFS

Sequence in context: A239415 A106130 A216828 * A036457 A030630 A068350

Adjacent sequences:  A131561 A131562 A131563 * A131565 A131566 A131567

KEYWORD

nonn

AUTHOR

J. M. Bergot, Aug 27 2007

EXTENSIONS

Edited by Olivier Gérard, Sep 27 2007

STATUS

approved

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Last modified September 18 23:06 EDT 2020. Contains 337174 sequences. (Running on oeis4.)