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A359076
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Numbers that have at least two proper divisors with an equal sum of digits.
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3
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20, 22, 24, 30, 36, 40, 42, 44, 48, 50, 52, 54, 60, 63, 66, 70, 72, 80, 81, 84, 88, 90, 96, 100, 102, 104, 105, 108, 110, 112, 115, 120, 124, 126, 130, 132, 135, 136, 140, 144, 147, 150, 154, 156, 160, 162, 165, 168, 170, 175, 176, 180, 189, 190, 192, 198, 200
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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24 is a term since its proper divisors 3 and 12 have an equal sum of digits.
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MAPLE
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q:= n-> (s-> is(nops(s)>nops({s[]})))(map(x-> add(i, i=convert(x,
base, 10)), [(numtheory[divisors](n) minus {n})[]])):
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MATHEMATICA
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a={}; For[k=1, k<=210, k++, If[Length[Intersection[Table[Total[Part[IntegerDigits[Divisors[k]], i]], {i, DivisorSigma[0, k]-1}]]] < DivisorSigma[0, k]-1, AppendTo[a, k]]]; a
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PROG
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(PARI) isok(k) = my(d=setminus(Set(divisors(k)), [k])); #Set(apply(sumdigits, d)) < #d; \\ Michel Marcus, Dec 19 2022
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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