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A226118
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Numbers n such that sigma(tau(phi(n))) = phi(tau(sigma(n))).
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3
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1, 2, 136, 160, 170, 204, 240, 282, 716, 745, 1002, 1077, 1465, 1509, 1578, 1868, 2012, 2157, 2346, 2720, 2760, 3608, 3898, 4101, 4461, 4512, 5066, 5322, 5898, 6189, 7080, 7185, 7341, 7628, 7660, 8108, 8517, 8665, 8698, 8709, 8805, 8922, 8940, 9234, 9745, 9962
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OFFSET
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1,2
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LINKS
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EXAMPLE
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For n=9962 we have:
sigma(9962)=15876 -> tau(15876)=45 -> phi(45)=24.
phi(9962)=4672 -> tau(4672)=14 -> sigma(14)=24.
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MAPLE
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with(numtheory); A226118:=proc(q) local n;
for n from 1 to q do
if sigma(tau(phi(n)))=phi(tau(sigma(n))) then print(n);
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MATHEMATICA
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Select[Range[10000], EulerPhi[DivisorSigma[0, DivisorSigma[1, #]]] == DivisorSigma[ 1, DivisorSigma[ 0, EulerPhi[#]]]&] (* Harvey P. Dale, May 26 2016 *)
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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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