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A061653
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Relative class number h- of cyclotomic field Q(zeta_n).
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6
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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, 41241, 1, 76301, 9, 7, 17, 64, 1, 853513, 8, 69, 1, 3882809, 3, 11957417, 37, 11, 19, 1280, 2, 100146415
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OFFSET
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1,23
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COMMENTS
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Note that if n == 2 (mod 4), Q(zeta_n) is the same field as Q(zeta_{n/2}).
For prime p, p divides a(p) (or a(2p)) if and only if p is in A000928.
For prime p, p divides a(4p) if and only if p is in A250216. (End)
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LINKS
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FORMULA
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EXAMPLE
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Q(zeta_23) = 3 is the first time that h- is bigger than 1.
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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EXTENSIONS
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Washington gives an extensive table on pp. 353-360.
a(59) changed from 41421 to 41241 (given correctly in 2nd edition of Washington), Matthew Johnson, Jul 20 2013
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STATUS
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approved
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