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A204830
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Numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.
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13
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120, 180, 240, 360, 420, 480, 504, 540, 600, 660, 672, 720, 780, 840, 960, 1080, 1260, 1320, 1440, 1512, 1560, 1584, 1620, 1680, 1800, 1848, 1890, 1920, 1980, 2016, 2040, 2160, 2184, 2280, 2340, 2352, 2376, 2400, 2520, 2640, 2688, 2760, 2772, 2856, 2880, 2940, 3000
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OFFSET
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1,1
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COMMENTS
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If m is a term then so is m*p^k when p is coprime to m. - David A. Corneth, Mar 09 2024
Is this sequence equal to the sequence: "Numbers k such that sigma(k) is divisible by 3 and sigma(k) >= 3*k"? - David A. Corneth, Mar 17 2024
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LINKS
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EXAMPLE
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180 is a term because sigma(180)/3 = 182 = 2 + 180 = 1+3+4+5+6+9+10+15+18+30+36+45 = 12+20+60+90 (summands are all the divisors of 180).
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CROSSREFS
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Cf. A023197, A083207 (Zumkeller numbers -- numbers k whose divisors can be partitioned into two disjoint sets whose sums are both sigma(k)/2), A087943, A204831 (numbers k whose divisors can be partitioned into four disjoint sets whose sums are all sigma(k)/4).
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KEYWORD
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nonn,changed
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AUTHOR
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STATUS
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approved
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