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A103578
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Number of divisors of m^2, where m is the smallest number with at least n divisors.
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1
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1, 3, 5, 9, 15, 15, 21, 21, 25, 27, 45, 45, 63, 63, 63, 63, 75, 75, 81, 81, 105, 105, 105, 105, 135, 135, 135, 135, 135, 135, 189, 189, 225, 225, 225, 225, 243, 243, 243, 243, 315, 315, 315, 315, 315, 315, 315, 315, 405, 405, 405, 405, 405, 405, 405, 405, 405
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n)=A000005((A061799(n))^2). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 01 2008]
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EXAMPLE
| a(8) = 21 because smallest number with 8 divisors is 24, 24^2 = 576 and 576 has 21 divisors.
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MATHEMATICA
| a = {}; i = 1; For[n = 1, n < 60, n++, While[DivisorSigma[0, i] < n, i++ ]; AppendTo[a, DivisorSigma[0, i^2]]]; a [From Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 31 2008]
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CROSSREFS
| Cf. A141264.
Sequence in context: A053993 A071155 A120695 * A116649 A129771 A093688
Adjacent sequences: A103575 A103576 A103577 * A103579 A103580 A103581
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KEYWORD
| nonn
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AUTHOR
| Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Aug 31 2008
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EXTENSIONS
| Edited by R. J. Mathar, Sep 01 2008, Dec 15 2008
Extended beyond a(8) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 31 2008
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