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A294888
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Sum of nonabundant proper divisors of n.
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8
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0, 1, 1, 3, 1, 6, 1, 7, 4, 8, 1, 16, 1, 10, 9, 15, 1, 21, 1, 22, 11, 14, 1, 24, 6, 16, 13, 28, 1, 42, 1, 31, 15, 20, 13, 25, 1, 22, 17, 30, 1, 54, 1, 40, 33, 26, 1, 40, 8, 43, 21, 46, 1, 48, 17, 64, 23, 32, 1, 46, 1, 34, 41, 63, 19, 78, 1, 58, 27, 74, 1, 33, 1, 40, 49, 64, 19, 90, 1, 46, 40, 44, 1, 86, 23, 46, 33, 92, 1, 96, 21
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OFFSET
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1,4
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COMMENTS
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Sum of divisors of n smaller than n that are nonabundant numbers (in A263837).
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LINKS
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FORMULA
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a(n) = Sum_{d|n, d<n} A294935(d)*d.
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EXAMPLE
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Proper divisors of 90 are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45. Of these 1, 2, 3, 5, 6, 9, 10, 15 and 45 are in A263837, thus a(90) = 1+2+3+5+6+9+10+15+45 = 96.
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MATHEMATICA
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a[n_] := DivisorSum[n, Boole[# < n && DivisorSigma[1, #] <= 2#] * #&];
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PROG
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(PARI) A294888(n) = sumdiv(n, d, (d<n)*(sigma(d)<=(2*d))*d);
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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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