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A096889
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Initial values for f(x)=phi(sigma(x)) such that iteration of f ends in cycle of length=15.
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10
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467856, 480200, 490000, 499968, 514416, 523344, 524352, 531441, 548400, 549444, 550512, 553728, 556752, 560532, 562500, 562800, 570000, 570276, 570576, 573744, 576240, 579024, 579900, 581700, 584112, 584836, 586756, 590268, 595008, 599076
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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MATHEMATICA
| g[n_] := EulerPhi[ DivisorSigma[1, n]]; f[n_] := f[n] = Block[{lst = NestWhileList[g, n, UnsameQ, All ]}, -Subtract @@ Flatten[ Position[lst, lst[[ -1]]]]]; Select[ Range[599800], f[ # ] == 15 &]
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CROSSREFS
| Cf. A000010, A000203, A095952, A096887, A095953, A096526, A095954, A096888, A096890, A095955, A095956.
Sequence in context: A205765 A206759 A051594 * A206205 A092010 A206541
Adjacent sequences: A096886 A096887 A096888 * A096890 A096891 A096892
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu) and Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 14 2004
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