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A162143 a(n) = A007304(n)^2. 9
900, 1764, 4356, 4900, 6084, 10404, 11025, 12100, 12996, 16900, 19044, 23716, 27225, 28900, 30276, 33124, 34596, 36100, 38025, 49284, 52900, 53361, 56644, 60516, 65025, 66564, 70756, 74529, 79524, 81225, 81796, 84100, 96100, 101124 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers that are the product of exactly 3 distinct squares of primes (p^2*q^2*r^2).

A050326(a(n)) = 8. - Reinhard Zumkeller, May 03 2013

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Index to sequences related to prime signature

EXAMPLE

900=2^2*3^2*5^2, 1764=2^2*3^2*7^2, 4356=2^2*3^2*11^2, ..

MATHEMATICA

fQ[n_]:=Last/@FactorInteger[n]=={2, 2, 2}; Select[Range[100000], f]

CROSSREFS

Cf. A006881, A162142.

Sequence in context: A137490 A129575 A074853 * A258888 A246887 A232556

Adjacent sequences:  A162140 A162141 A162142 * A162144 A162145 A162146

KEYWORD

nonn,changed

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jun 25 2009

EXTENSIONS

Edited by N. J. A. Sloane, Jun 27 2009

STATUS

approved

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Last modified May 29 21:28 EDT 2017. Contains 287257 sequences.