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A002202
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Values taken by totient function phi(m) (A000010).
(Formerly M0987 N0371)
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44
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1, 2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 28, 30, 32, 36, 40, 42, 44, 46, 48, 52, 54, 56, 58, 60, 64, 66, 70, 72, 78, 80, 82, 84, 88, 92, 96, 100, 102, 104, 106, 108, 110, 112, 116, 120, 126, 128, 130, 132, 136, 138, 140, 144, 148, 150, 156, 160, 162, 164, 166, 168, 172, 176
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| These are the numbers n such that for some m the multiplicate group mod m has order n.
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REFERENCES
| J. W. L. Glaisher, Number-Divisor Tables. British Assoc. Math. Tables, Vol. 8, Camb. Univ. Press, 1940, p. 64.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| T. D. Noe, Table of n, a(n) for n = 1..10000
K. Ford, The distribution of totients, Electron. Res. Announc. Amer. Math. Soc. 4 (1998), 27-34.
Eric Weisstein's World of Mathematics, Totient Valence Function
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MAPLE
| with(numtheory); t1 := [seq(nops(invphi(n)), n=1..300)]; t2 := []: for n from 1 to 300 do if t1[n] <> 0 then t2 := [op(t2), n]; fi; od: t2;
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MATHEMATICA
| phiQ[m_] := Select[Range[m+1, 2m*Product[(1-1/(k*Log[k]))^(-1), {k, 2, DivisorSigma[0, m]}]], EulerPhi[#] == m &, 1 ] != {}; Select[Range[176], phiQ] (* From Jean-François Alcover, May 23 2011, after Maxim Rytin *)
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CROSSREFS
| Cf. A000010, A002180, A032446, A058277.
Sequence in context: A011860 A049445 A002174 * A049225 A076450 A097379
Adjacent sequences: A002199 A002200 A002201 * A002203 A002204 A002205
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KEYWORD
| nonn,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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