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A082729
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Least positive number that can be written using all divisors of n and the operations add and subtract.
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3
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1, 1, 2, 1, 4, 2, 6, 1, 5, 2, 10, 2, 12, 4, 6, 1, 16, 1, 18, 2, 10, 8, 22, 2, 19, 10, 14, 2, 28, 2, 30, 1, 18, 14, 22, 1, 36, 16, 22, 2, 40, 2, 42, 4, 12, 20, 46, 2, 41, 7, 30, 6, 52, 2, 38, 2, 34, 26, 58, 2, 60, 28, 22, 1, 46, 2, 66, 10, 42, 2, 70, 1, 72, 34, 26, 12, 58, 2, 78, 2, 41, 38, 82
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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Divisors of n=18: {1,2,3,6,9,18} -> a(18)=-1+2-3-6-9+18=1.
Divisors of n=15: {1,3,5,15} -> a(15)=-1-3-5+15=6, as
-1-3-5-15<1, 1-3-5-15<1, -1+3-5-15<1, 1+3-5-15<1, -1-3+5-15<1, 1-3+5-15<1,
-1+3+5-15<1, 1+3+5-15<1, 1-3-5+15>6, -1+3-5+15>6, 1+3-5+15>6, -1-3+5+15>6,
1-3+5+15>6, -1+3+5+15>6 and 1+3+5+15>6.
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PROG
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(PARI) for(n=1, 1000, nd=numdiv(n); d=divisors(n); nn=3048; for(j=0, 2^nd-1, s=0; for(h=0, nd-1, if(bittest(j, h)==0, s=s-d[h+1], s=s+d[h+1])); if(s>0, if(s<nn, nn=s))); write("b082729.txt", n " " nn)) /* Donovan Johnson, Sep 14 2013 */
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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