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A061653
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Relative class number h- of cyclotomic field Q(zeta_n).
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5
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 8, 1, 9, 1, 1, 1, 1, 1, 37, 1, 2, 1, 121, 1, 211, 1, 1, 3, 695, 1, 43, 1, 5, 3, 4889, 1, 10, 2, 9, 8, 41421, 1, 76301, 9, 7, 17, 64, 1, 853513, 8, 69, 1, 3882809, 3, 11957417, 37, 11, 19, 1280, 2, 100146415
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,23
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COMMENTS
| Note that if n == 2 (mod 4), Q(zeta_n) is the same field as Q(zeta_{n/2}).
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REFERENCES
| L. C. Washington, Introduction to Cyclotomic Fields, Springer, p. 353.
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LINKS
| R. J. Mathar, Table of n, a(n) for n = 1..162
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EXAMPLE
| Q(zeta_23) = 3 is the first time that h- is bigger than 1.
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CROSSREFS
| Cf. A035115, A055513, A061494, A005848.
Sequence in context: A046556 A046535 A135939 * A069226 A016565 A051714
Adjacent sequences: A061650 A061651 A061652 * A061654 A061655 A061656
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KEYWORD
| nonn,easy,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jun 16 2001
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EXTENSIONS
| Washington gives an extensive table on pp. 353-360.
Missing term a(1) = 1 inserted by N. J. A. Sloane (njas(AT)research.att.com), Feb 05 2009 at the suggestion of Tanya Khovanova
More terms from R. J. Mathar, Feb 06 2009
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