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Search: id:A141801
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| A141801 |
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For n>=2, a(n) = sum{k=1 to n} (largest prime dividing (n*k)). a(1)=0. |
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+0
2
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OFFSET
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1,2
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EXAMPLE
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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.
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CROSSREFS
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Cf. A141800.
Sequence in context: A014719 A139417 A095873 this_sequence A081949 A091657 A088037
Adjacent sequences: A141798 A141799 A141800 this_sequence A141802 A141803 A141804
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KEYWORD
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more,nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jul 05 2008
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