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Search: id:A096890
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| A096890 |
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Initial values for f(x)=phi(sigma(x)) such that iteration of f ends in cycle of length=18. |
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+0
14
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| 401408, 414050, 436032, 455625, 462400, 466608, 476100, 486300, 486900, 512337, 522242, 526974, 543600, 544644, 544944, 546192, 546861, 554304, 559504, 571536, 572313, 575028, 577200, 579856, 583200, 585528, 599694, 604300, 609429, 611618
(list; graph; listen)
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OFFSET
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1,1
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MATHEMATICA
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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[624900], f[ # ] == 18 &]
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CROSSREFS
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Cf. A000010, A000203, A095952, A096887, A095953, A096526, A095954, A096888, A096889, A095955, A095956.
Sequence in context: A050434 A015424 A083634 this_sequence A157826 A043609 A078519
Adjacent sequences: A096887 A096888 A096889 this_sequence A096891 A096892 A096893
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu) and Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 14 2004
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