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A189982 Numbers with prime factorization pqrs^2. 1
420, 630, 660, 780, 924, 990, 1020, 1050, 1092, 1140, 1170, 1380, 1386, 1428, 1470, 1530, 1540, 1596, 1638, 1650, 1710, 1716, 1740, 1820, 1860, 1932, 1950, 2070, 2142, 2220, 2244, 2380, 2394, 2436, 2460, 2508, 2550, 2574, 2580, 2604, 2610, 2652, 2660, 2790 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

Will Nicholes, Prime Signatures

MATHEMATICA

f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1, 1, 2}; Select[Range[4000], f]

CROSSREFS

Cf. A178739, A189975.

Sequence in context: A069064 A024410 A200521 * A070237 A156687 A191934

Adjacent sequences:  A189979 A189980 A189981 * A189983 A189984 A189985

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 03 2011

STATUS

approved

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Last modified May 25 07:27 EDT 2013. Contains 225646 sequences.