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 A141801 For n>=2, a(n) = Sum_{k=1..n} (largest prime dividing (n*k)), a(1)=0. 1
 0, 4, 9, 9, 25, 20, 49, 26, 33, 52, 121, 52, 169, 108, 93, 75, 289, 100, 361, 144, 179, 258, 529, 168, 195, 358, 189, 254, 841, 254, 961, 258, 431, 612, 363, 302, 1369, 766, 595, 404, 1681, 494, 1849, 656, 511, 1124, 2209, 556, 639, 598, 1009, 870, 2809, 654, 875 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE For n = 4, the largest prime dividing 1*4=4 is 2. The largest prime dividing 2*4=8 is 2. The largest prime dividing 3*4=12 is 3. And the largest prime dividing 4*4=16 is 2. So a(4) = 2+2+3+2 = 9. CROSSREFS Cf. A141800. Sequence in context: A139417 A298816 A095873 * A177083 A081949 A091657 Adjacent sequences:  A141798 A141799 A141800 * A141802 A141803 A141804 KEYWORD nonn AUTHOR Leroy Quet, Jul 05 2008 EXTENSIONS Extended by Ray Chandler, Jun 22 2009 STATUS approved

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Last modified October 15 07:46 EDT 2019. Contains 328026 sequences. (Running on oeis4.)