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A126974
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a(1)=0. a(2)=1. a(n) = a(d(n)) + a(phi(n)), where d(n) = A000005(n), phi(n) = A000010(n).
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0
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0, 1, 2, 3, 4, 4, 5, 6, 6, 6, 7, 7, 8, 7, 9, 10, 11, 8, 9, 10, 10, 9, 10, 12, 12, 10, 11, 11, 12, 12, 13, 14, 13, 13, 15, 13, 14, 11, 15, 16, 17, 13, 14, 14, 16, 12, 13, 16, 15, 14, 17, 16, 17, 14, 19, 18, 16, 14, 15, 17, 18, 15, 17, 19, 19, 16, 17, 18, 17, 18, 19, 19, 20, 16, 20
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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MAPLE
| with(numtheory): a[1]:=0: a[2]:=1: for n from 3 to 90 do a[n]:=a[tau(n)]+a[phi(n)] od: seq(a[n], n=1..90); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 24 2007
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MATHEMATICA
| f[l_List] := Block[{n = Length[l] + 1}, Append[l, l[[DivisorSigma[0, n]]] + l[[EulerPhi[n]]]]]; Nest[f, {0, 1}, 75] (*Chandler*)
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CROSSREFS
| Cf. A000005, A000010.
Sequence in context: A125568 A108872 A147847 * A089058 A187103 A080444
Adjacent sequences: A126971 A126972 A126973 * A126975 A126976 A126977
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Mar 20 2007
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and Ray Chandler (rayjchandler(AT)sbcglobal.net), Mar 24 2007
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