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A084680
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Order of 10 modulo n [i.e. least m such that 10^m = 1 (mod n)] or 0 when no such number exists.
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4
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1, 0, 1, 0, 0, 0, 6, 0, 1, 0, 2, 0, 6, 0, 0, 0, 16, 0, 18, 0, 6, 0, 22, 0, 0, 0, 3, 0, 28, 0, 15, 0, 2, 0, 0, 0, 3, 0, 6, 0, 5, 0, 21, 0, 0, 0, 46, 0, 42, 0, 16, 0, 13, 0, 0, 0, 18, 0, 58, 0, 60, 0, 6, 0, 0, 0, 33, 0, 22, 0, 35, 0, 8, 0, 0, 0, 6, 0, 13, 0, 9, 0, 41, 0, 0, 0, 28, 0, 44, 0, 6, 0, 15, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,7
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COMMENTS
| When n is not divisible by 2 or 5, a(n) = A007732(n). A002329 contains the nonzero terms.
A number k>0 appears in this sequence exactly A059892(k) times. - T. D. Noe (noe(AT)sspectra.com), May 18 2007
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000
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MAPLE
| A084680 := proc(n) if gcd(n, 10) <> 1 then 0 ; elif n = 1 then 1 ; else numtheory[order](10, n) ; end if; end proc: seq(A084680(n), n=2..100) ; # R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 10 2010
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CROSSREFS
| Cf. A007732, A002329.
Sequence in context: A192072 A060297 A137378 * A051626 A200229 A137785
Adjacent sequences: A084677 A084678 A084679 * A084681 A084682 A084683
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KEYWORD
| nonn
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AUTHOR
| Lekraj Beedassy (blekraj(AT)yahoo.com), Jun 30 2003
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EXTENSIONS
| More terms from John W. Layman (layman(AT)math.vt.edu), Aug 12 2003
Removed duplicate of a comment. Added Maple program - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 10 2010
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