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Search: id:A131564
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| A131564 |
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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). |
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1
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| 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
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OFFSET
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1,1
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EXAMPLE
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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.
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CROSSREFS
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Sequence in context: A066722 A080862 A106130 this_sequence A036457 A030630 A068350
Adjacent sequences: A131561 A131562 A131563 this_sequence A131565 A131566 A131567
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KEYWORD
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nonn
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), Aug 27 2007
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EXTENSIONS
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Edited by Olivier Gerard (olivier.gerard(AT)gmail.com), Sep 27 2007
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