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Search: id:A158804
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| A158804 |
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Composite integers n which are a multiple of the sum of their prime factors. |
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+0
1
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| 4, 8, 9, 16, 25, 27, 30, 32, 49, 60, 64, 70, 81, 84, 90, 105, 120, 121, 125, 128, 140, 150, 168, 169, 180, 231, 234, 240, 243, 252, 256, 260, 270, 280, 286, 289, 300, 315, 336, 343, 350, 360, 361, 450, 456, 468, 480, 490, 504, 512, 520, 525, 528, 529, 532, 540
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Jean-Marie de Koninck, Florian Luca, Integers divisible by the sum of their prime factors, Mathematika 52 (1&2) (2005) 69-77, MR2261843.
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FORMULA
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{n in A002808: A008472(n)|n }
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EXAMPLE
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4 is in the sequence because A008472(4)=2 divides 4. 5 is not in the sequence because it is prime. 6 is not in the sequence because A008472(6)=5 does not divide 6.
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MAPLE
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A008472 := proc(n) numtheory[factorset](n) ; add(d, d=%) ; end: isbeta := proc(n) if isprime(n) then false; else if n mod A008472(n) = 0 then true; else false; fi; fi; end: for n from 2 to 1200 do if isbeta(n) then printf("%d, ", n); fi; od:
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CROSSREFS
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Sequence in context: A140104 A127398 A109422 this_sequence A080366 A001694 A157985
Adjacent sequences: A158801 A158802 A158803 this_sequence A158805 A158806 A158807
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KEYWORD
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easy,nonn
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AUTHOR
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R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 27 2009
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