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A169644 Numbers with two or more distinct factorizations m*k such that m <= k <= 2*m. 0
72, 120, 144, 180, 240, 252, 288, 336, 360, 378, 400, 420, 432, 450, 480, 504, 540, 576, 594, 600, 630, 648, 660, 672, 700, 720, 756, 780, 792, 800, 840, 858, 864, 900, 924, 936, 960, 1008, 1050, 1056, 1080, 1092, 1120, 1152, 1170, 1188, 1200, 1225, 1248 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that A067742(n) >= 3.

The smallest number with 3 such factorizations is 840 = 28*30 = 24*35 = 21*40.

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

72 = 8 * 9 = 6 * 12, so it is in the sequence. 60 = 6 * 10, but the next closest factorization is 5 * 12 and 12 > 2*5, so 60 is not in the sequence.

CROSSREFS

Cf. A067742, A071562, A100345.

Sequence in context: A143610 A166987 A251124 * A078667 A090784 A291805

Adjacent sequences:  A169641 A169642 A169643 * A169645 A169646 A169647

KEYWORD

nonn

AUTHOR

Franklin T. Adams-Watters, Apr 04 2010

STATUS

approved

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Last modified September 27 15:29 EDT 2020. Contains 337383 sequences. (Running on oeis4.)