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A372834
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a(n) is the numerator of Sum_{d|n, d < sqrt(n)} 1/d.
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1
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0, 1, 1, 1, 1, 3, 1, 3, 1, 3, 1, 11, 1, 3, 4, 3, 1, 11, 1, 7, 4, 3, 1, 25, 1, 3, 4, 7, 1, 61, 1, 7, 4, 3, 6, 25, 1, 3, 4, 39, 1, 2, 1, 7, 23, 3, 1, 9, 1, 17, 4, 7, 1, 2, 6, 53, 4, 3, 1, 49, 1, 3, 31, 7, 6, 2, 1, 7, 4, 129, 1, 19, 1, 3, 23, 7, 8, 2, 1, 83
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OFFSET
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1,6
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LINKS
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FORMULA
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Numerators of coefficients in expansion of Sum_{k>=1} x^(k*(k+1)) / (k * (1 - x^k)).
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EXAMPLE
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0, 1, 1, 1, 1, 3/2, 1, 3/2, 1, 3/2, 1, 11/6, 1, 3/2, 4/3, 3/2, 1, 11/6, ...
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MATHEMATICA
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nmax = 80; CoefficientList[Series[Sum[x^(k (k + 1))/(k (1 - x^k)), {k, 1, nmax}], {x, 0, nmax}], x] // Numerator // Rest
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PROG
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(PARI) a(n) = numerator(sumdiv(n, d, if (d^2 < n, 1/d))); \\ Michel Marcus, May 14 2024
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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