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A023884
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Average of divisors except itself is an integer.
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6
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2, 3, 5, 6, 7, 9, 11, 13, 15, 17, 19, 23, 25, 29, 30, 31, 33, 37, 41, 43, 44, 47, 49, 51, 53, 59, 61, 67, 69, 71, 73, 79, 81, 83, 87, 89, 91, 97, 101, 103, 107, 109, 113, 114, 117, 120, 121, 123, 124, 127, 131, 133, 135, 137, 139, 141, 149, 151, 157, 159
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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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MAPLE
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q:=n->(irem(numtheory[sigma](n)-n, numtheory[tau](n)-1)=0):
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MATHEMATICA
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Select[Range[2000], IntegerQ[Mean[Most[Divisors[#]]]]&] (* Daniel Lignon, Feb 26 2015 *)
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PROG
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(PARI) isok(n) = (n != 1) && !((sigma(n) - n) % (numdiv(n)-1)); \\ Michel Marcus, Mar 01 2015
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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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