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A137490 Numbers with 27 divisors. 1
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; text; internal format)
OFFSET

1,1

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. - R. J. Mathar, Mar 01 2010

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

A000005(a(n))=27.

MATHEMATICA

Select[Range[150000], DivisorSigma[0, #]==27&] (* Vladimir Joseph Stephan Orlovsky, May 06 2011 *)

PROG

(PARI) isA137490(n) = numdiv(n)==27 \\ Michael B. Porter, Apr 10 2010

CROSSREFS

Cf. A030513..A030516, A030626, A030627, A030634..A030638, A005179, A003680, A096932, A061286, A061283.

Sequence in context: A061044 A127658 A318720 * A129575 A328136 A321206

Adjacent sequences:  A137487 A137488 A137489 * A137491 A137492 A137493

KEYWORD

nonn

AUTHOR

R. J. Mathar, Apr 22 2008

STATUS

approved

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Last modified October 20 02:01 EDT 2019. Contains 328244 sequences. (Running on oeis4.)