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A328236
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The least m > 1 such that the arithmetic derivative of m*n is a multiple of the arithmetic derivative of n.
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5
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2, 2, 2, 2, 6, 2, 8, 4, 10, 2, 4, 2, 14, 12, 4, 2, 10, 2, 8, 21, 22, 2, 24, 4, 26, 2, 12, 2, 30, 2, 6, 33, 34, 8, 6, 2, 18, 12, 40, 2, 42, 2, 8, 22, 46, 2, 10, 4, 14, 32, 33, 2, 8, 12, 56, 24, 30, 2, 56, 2, 62, 40, 8, 65, 66, 2, 65, 69, 70, 2, 22, 2, 45, 24, 32, 65, 78, 2, 24, 4, 82, 2, 30, 24, 50, 16, 88, 2, 42, 32, 20, 40
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OFFSET
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2,1
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LINKS
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EXAMPLE
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Arithmetic derivative of 6 is 6' = A003415(6) = 5. Taking arithmetic derivatives of successive multiples of six we obtain 12' = 16, 18' = 21, 24' = 44, 30' = 31, and not until with A003415(6*6) = 36' = 60 we obtain a multiple of 5. Thus a(6) = 6.
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PROG
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(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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