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A137490
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Numbers with 27 divisors.
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1
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900, 1764, 2304, 4356, 4900, 6084, 6400, 10404, 11025, 12100, 12544, 12996, 16900, 19044, 23716, 26244, 27225, 28900, 30276, 30976, 33124, 34596, 36100, 38025, 43264, 49284, 52900, 53361, 56644, 60516, 65025, 66564, 70756, 73984, 74529
(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^26 (subset of A089081), p^2*q^2*r^2 (like 900, 1764, 4356, squares of A007304) or p^2*q^8 (like 2304, 6400, subset of the squares of A030628) 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
| Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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FORMULA
| A000005(a(n))=27.
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MATHEMATICA
| Select[Range[150000], DivisorSigma[0, #]==27&] (* From Vladimir Joseph Stephan Orlovsky, May 06 2011 *)
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PROG
| (PARI) isA137490(n) = numdiv(n)==27 [From Michael B. Porter (michael_b_porter(AT)yahoo.com), Apr 10 2010]
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CROSSREFS
| Cf. A030513-A030516, A030626, A030627, A030634-A030638, A005179, A003680, A096932, A061286, A061283.
Sequence in context: A158409 A061044 A127658 * A129575 A074853 A162143
Adjacent sequences: A137487 A137488 A137489 * A137491 A137492 A137493
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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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