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A030638
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Numbers with 20 divisors.
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16
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240, 336, 432, 528, 560, 624, 648, 810, 816, 880, 912, 1040, 1104, 1134, 1232, 1360, 1392, 1456, 1488, 1520, 1536, 1776, 1782, 1840, 1904, 1968, 2000, 2064, 2106, 2128, 2256, 2288, 2320, 2480, 2544, 2560, 2576, 2754, 2832, 2835, 2928
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Numbers of the form p^19, p*q^9, p*q*r^4 (A179644) or p^3*q^4 (A179666), where p, q and r are distinct primes. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 01 2010]
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LINKS
| R. J. Mathar, Table of n, a(n) for n = 1..1000
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MATHEMATICA
| Select[Range[20000], DivisorSigma[0, #]==20&] (* From Vladimir Joseph Stephan Orlovsky, May 05 2011 *)
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CROSSREFS
| Cf. A030636, A030637, A137484.
Sequence in context: A135194 A031173 A067373 * A179644 A099833 A179440
Adjacent sequences: A030635 A030636 A030637 * A030639 A030640 A030641
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KEYWORD
| nonn
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AUTHOR
| Jeff Burch (jmburch(AT)osprey.smcm.edu)
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