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A137484
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Numbers with 21 divisors.
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6
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576, 1600, 2916, 3136, 7744, 10816, 18225, 18496, 23104, 33856, 35721, 53824, 61504, 62500, 87616, 88209, 107584, 118336, 123201, 140625, 141376, 179776, 210681, 222784, 238144, 263169, 287296, 322624, 341056, 385641, 399424, 440896
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Maple implementation: see A030513.
Numbers of the form p^20 or p^2*q^6 (A189990) where p and q are distinct primes. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 01 2010]
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LINKS
| T. D. Noe, Table of n, a(n) for n = 1..1000
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FORMULA
| A000005(a(n))=21.
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MATHEMATICA
| Select[Range[450000], DivisorSigma[0, #]==21&] (* From Vladimir Joseph Stephan Orlovsky, May 03 2011 *)
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CROSSREFS
| Cf. A030513-A030516, A030626, A030627, A030634-A030638, A005179, A003680, A096932, A061286, A061283.
Sequence in context: A064253 A069266 A060678 * A189990 A064254 A067225
Adjacent sequences: A137481 A137482 A137483 * A137485 A137486 A137487
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KEYWORD
| nonn
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AUTHOR
| R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 22 2008
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