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Search: id:A138224
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| A138224 |
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a(n) = the nearest divisor of n to the number of positive divisors of n. In case of tie, round down. |
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+0
4
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| 1, 2, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 2, 3, 4, 1, 6, 1, 5, 3, 2, 1, 8, 1, 2, 3, 7, 1, 6, 1, 4, 3, 2, 5, 9, 1, 2, 3, 8, 1, 7, 1, 4, 5, 2, 1, 8, 1, 5, 3, 4, 1, 9, 5, 8, 3, 2, 1, 12, 1, 2, 7, 8, 5, 6, 1, 4, 3, 7, 1, 12, 1, 2, 5, 4, 1, 6, 1, 10, 3, 2, 1, 12, 5, 2, 3, 8, 1, 10, 1, 4, 3, 2, 5, 12, 1, 7, 3, 10, 1, 6
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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There are four positive divisors of 15: (1,3,5,15). There are two divisors, 3 and 5, that are nearest 4. We take the smaller divisor, 3 in this case, in case of a tie; so a(15) = 3.
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MAPLE
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A138224 := proc(n) if n = 1 then RETURN(1); fi; t := numtheory[tau](n) ; dvs := sort(convert(numtheory[divisors](n), list)) ; a := op(1, dvs) ; for i from 2 to nops(dvs) do if abs(op(i, dvs) - t) < abs(a-t) then a := op(i, dvs) ; fi; od: a ; end: seq(A138224(n), n=1..120) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 20 2009]
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CROSSREFS
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Cf. A138221, A138222, A138223, A000005.
Sequence in context: A029216 A153174 A138222 this_sequence A046205 A046206 A137753
Adjacent sequences: A138221 A138222 A138223 this_sequence A138225 A138226 A138227
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, Mar 06 2008
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EXTENSIONS
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Extended beyond a(15) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 20 2009
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