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Search: id:A085091
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| A085091 |
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Denominator of Sum_{i=2..t} (d(i)/d(i-1)-1), where d(1), ..., d(t) are the divisors of n. |
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+0
2
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| 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 3, 1, 2, 3, 1, 1, 1, 1, 4, 3, 2, 1, 6, 1, 2, 1, 4, 1, 15, 1, 1, 3, 2, 5, 3, 1, 2, 3, 10, 1, 6, 1, 4, 15, 2, 1, 1, 1, 1, 3, 4, 1, 2, 5, 14, 3, 2, 1, 30, 1, 2, 21, 1, 5, 6, 1, 4, 3, 35, 1, 24, 1, 2, 3, 4, 7, 6, 1, 20, 1, 2, 1, 7, 5, 2, 3, 8, 1, 45, 7, 4, 3, 2, 5, 6, 1, 1, 9, 2, 1
(list; graph; listen)
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OFFSET
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1,6
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REFERENCES
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M. D. Vose, Integers with consecutive divisors in small ratio, J. Number Theory, 19 (1984), 233-238.
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EXAMPLE
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0, 1, 2, 2, 4, 5/2, 6, 3, 4, 7/2, 10, 10/3, 12, 9/2, 14/3, ...
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MAPLE
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with(numtheory): f := proc(n) local t1, t2, t3, i; t1 := divisors(n); t3 := convert(t1, list); t2 := 0; for i from 2 to nops(t3) do t2 := t2+(t3[i]/t3[i-1]-1); od; t2; end;
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CROSSREFS
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Cf. A085085.
Sequence in context: A066882 A068347 A025865 this_sequence A052128 A114536 A138010
Adjacent sequences: A085088 A085089 A085090 this_sequence A085092 A085093 A085094
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KEYWORD
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nonn,frac
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Aug 11 2003
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