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A059889
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a(n)=|{m : multiplicative order of 7 mod m=n}|.
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1
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4, 6, 8, 26, 4, 42, 12, 48, 52, 66, 12, 778, 4, 138, 80, 300, 12, 528, 12, 1430, 72, 138, 28, 15216, 24, 66, 1216, 966, 28, 3630, 28, 1344, 360, 58, 108, 16988, 28, 138, 176, 12752
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The multiplicative order of a mod m, gcd(a,m)=1, is the smallest natural number d for which a^d = 1 (mod m). a(n)=number of orders of degree n monic irreducible polynomials over GF(7).
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FORMULA
| a(n)=Sum_{d|n} mu(n/d)*tau(7^d-1), (mu(n) = Moebius function A008683, tau(n) = number of divisors of n A000005).
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CROSSREFS
| Cf. A000005, A008683, A058946, A053450, A058946, A059499, A059885-A059888, A059890-A059892.
Sequence in context: A106366 A019160 A126233 * A058011 A089330 A108270
Adjacent sequences: A059886 A059887 A059888 * A059890 A059891 A059892
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 06 2001
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