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A210937
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Decimal expansion of the continued fraction 1'+1/(2'+2/(3'+3/...)), where n' is the arithmetic derivative of n.
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1
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4, 2, 1, 4, 7, 8, 1, 6, 1, 2, 9, 8, 8, 6, 7, 3, 0, 9, 0, 6, 2, 0, 0, 9, 1, 1, 0, 4, 1, 1, 2, 1, 3, 6, 4, 3, 1, 1, 1, 4, 6, 0, 3, 3, 5, 0, 7, 7, 6, 8, 0, 9, 0, 3, 9, 6, 8, 4, 3, 3, 7, 4, 7, 8, 7, 9, 0, 8, 7, 9, 1, 4, 5, 4, 0, 0, 2, 2, 2, 0, 4, 8, 8, 1, 6, 9, 0, 0, 8, 5, 8, 7, 0, 5, 4, 9, 6, 8, 4, 4, 7, 5, 3, 5, 8, 2, 8, 2, 4, 3, 0, 7, 7, 2, 5, 0, 5, 0, 2, 4, 2, 5, 4, 2, 5, 8, 2, 8, 2
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OFFSET
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0,1
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COMMENTS
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A good approximation up to the 9th decimal digit is 4796/11379.
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REFERENCES
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1
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LINKS
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EXAMPLE
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0.42147816129886730906200911...
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MAPLE
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with(numtheory);
local a, b, c, I, p, pfs;
b:=1;
for i from n by -1 to 2 do
pfs:=ifactors(i)[2]; a:=i*add(op(2, p)/op(1, p), p=pfs); b:=1/b*a+i;
od;
print(evalf(b, 500));
end:
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MATHEMATICA
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digits = 129; d[0] = d[1] = 0; d[n_] := d[n] = n*Total[Apply[#2/#1&, FactorInteger[n], {1}]]; f[m_] := f[m] = Fold[d[#2]+#2/#1&, 1, Range[m] // Reverse] // RealDigits[#, 10, digits]& // First; f[digits]; f[m = 2digits]; While[f[m] != f[m/2], m = 2m]; f[m] (* Jean-François Alcover, Feb 21 2014 *)
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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