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 A077095 Starting iteration of Phi[]*(Sigma[]-Phi[]) function at these initial values leads to the fixed point 24. 0
 24, 42, 69, 74, 75, 82, 86, 94, 115, 125, 133, 155, 185, 187, 203, 289, 299, 323, 341, 361, 377, 437, 1681 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Probably this sequence is finite, with 23 terms of which the last is 1681. LINKS Table of n, a(n) for n=1..23. EXAMPLE n=1641: FixedPointList={1681,82,42,24},end=24. MATHEMATICA f[x_] := EulerPhi[DivisorSigma[1, x]-EulerPhi[x]] Do[s=NestList[f, n, 100]; s1=Part[s, 99]; s2=Part[s, 100]; If[Equal[s1, s2]&&Equal[s1, 4], Print[{n, s1}]], {n, 1, 1000000}] fp24Q[n_]:=FixedPoint[EulerPhi[DivisorSigma[1, #]-EulerPhi[#]]&, n, 20]==24; Select[ Range[1700], fp24Q] (* Harvey P. Dale, Mar 12 2023 *) CROSSREFS Cf. A077090-A077100. Sequence in context: A274350 A063702 A074975 * A228844 A111948 A039411 Adjacent sequences: A077092 A077093 A077094 * A077096 A077097 A077098 KEYWORD nonn,fini,full AUTHOR Labos Elemer, Oct 31 2002 STATUS approved

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Last modified June 24 00:02 EDT 2024. Contains 373661 sequences. (Running on oeis4.)