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A061653 Relative class number h- of cyclotomic field Q(zeta_n). 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,23

COMMENTS

Note that if n == 2 (mod 4), Q(zeta_n) is the same field as Q(zeta_{n/2}).

REFERENCES

L. C. Washington, Introduction to Cyclotomic Fields, Springer, p. 353.

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..162

EXAMPLE

Q(zeta_23) = 3 is the first time that h- is bigger than 1.

CROSSREFS

Cf. A035115, A055513, A061494, A005848.

Sequence in context: A046556 A046535 A135939 * A069226 A016565 A051714

Adjacent sequences:  A061650 A061651 A061652 * A061654 A061655 A061656

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane, Jun 16 2001

EXTENSIONS

Washington gives an extensive table on pp. 353-360.

Missing term a(1) = 1 inserted by N. J. A. Sloane, Feb 05 2009 at the suggestion of Tanya Khovanova

More terms from R. J. Mathar, Feb 06 2009

Changed a(59) from 41421 to 41241 (given correctly in 2nd edition of Washington), Matthew Johnson, Jul 20 2013

STATUS

approved

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Last modified June 29 01:46 EDT 2017. Contains 288856 sequences.