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A217773
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Numbers n such that tau(n) = tau(n+1) and phi(n) = phi(n+1).
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1
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104, 3255, 22935, 983775, 1025504, 2200694, 2619705, 4163355, 4447064, 4695704, 6372794, 9718904, 11903775, 23992215, 26879684, 29357475, 37239735, 40588485, 41207144, 48615735, 56424555, 76466985, 81591194, 83864055, 113664135, 118018094, 166758015
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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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MATHEMATICA
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Select[Range[100000000], DivisorSigma[0, #] == DivisorSigma[0, # + 1] && EulerPhi[#] == EulerPhi[# + 1] &]
Position[Partition[Table[{DivisorSigma[0, n], EulerPhi[n]}, {n, 1668*10^5}], 2, 1], _?(#[[1]]==#[[2]]&), 1, Heads->False]//Flatten (* Harvey P. Dale, Nov 20 2019 *)
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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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