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A095952
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Initial values for f(x)=phi(sigma(x)) such that iteration of f ends in cycle of length=1.
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14
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1, 2, 3, 5, 8, 9, 12, 14, 15, 19, 20, 22, 23, 26, 29, 41, 43, 128, 156, 168, 186, 189, 200, 201, 217, 231, 237, 240, 248, 254, 260, 266, 271, 285, 291, 297, 303, 304, 313, 314, 329, 332, 335, 337, 341, 346, 350, 366, 368, 383, 387, 395, 413, 427, 430, 436, 437
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| n=100: trajectory={980, 648, 880, 720, 720}
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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[1540], f[ # ] == 1 &] (from Robert G. Wilson v Jul 14 2004)
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CROSSREFS
| Cf. A000010, A000203, A096887, A095953, A096526, A095954, A096888, A096889, A096890, A095955, A095956.
Sequence in context: A181155 A153081 A190841 * A025033 A122933 A091513
Adjacent sequences: A095949 A095950 A095951 * A095953 A095954 A095955
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jul 13 2004
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