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A075868
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tau(n) = phi(sum of prime factors of n).
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0
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3, 6, 15, 20, 21, 28, 35, 50, 66, 98, 99, 104, 105, 114, 125, 130, 154, 170, 210, 230, 276, 325, 351, 352, 363, 372, 374, 380, 414, 444, 459, 476, 532, 539, 558, 572, 580, 585, 608, 666, 693, 696, 845, 847, 950, 968, 975
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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EXAMPLE
| tau(50) = number of divisors of 50 = 6; phi(sum of prime factors of 50) = phi(2 + 5) = 6. Hence 50 is a term of the sequence.
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MATHEMATICA
| Select[Range[2, 10^3], EulerPhi[Apply[Plus, Transpose[FactorInteger[ # ]][[1]]]] == DivisorSigma[0, # ] &]
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CROSSREFS
| Sequence in context: A160724 A174279 A060304 * A162335 A095869 A069559
Adjacent sequences: A075865 A075866 A075867 * A075869 A075870 A075871
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Oct 15 2002
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