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A090556
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Beginning with 1, a(n) = least number m > a(n-1) such that phi(a(n-1)) divides phi(m).
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2
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1, 2, 3, 4, 5, 8, 10, 12, 13, 21, 26, 28, 35, 39, 45, 52, 56, 65, 97, 119, 153, 193, 221, 291, 357, 386, 388, 416, 442, 448, 476, 485, 579, 595, 663, 765, 769, 965, 1105, 1455, 1538, 1544, 1552, 1649, 1799, 2307, 2313, 2895, 3076, 3088, 3104, 3281, 3341, 3845, 4947
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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NestList[Function[n, SelectFirst[Range[n + 1, 10^4], Divisible[EulerPhi@ #, EulerPhi@ n] &]], 1, 54] (* Michael De Vlieger, May 01 2016, Version 10 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Corrected and extended by Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 03 2004
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STATUS
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approved
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