

A061494


Relative class number h of cyclotomic field Q(zeta_n) where n runs through positive integers not congruent to 2 (mod 4) [A042965, but omitting the initial 0].


2



1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 8, 9, 1, 1, 1, 1, 37, 2, 1, 121, 211, 1, 1, 695, 1, 43, 5, 3, 4889, 10, 2, 9, 41241, 1, 76301, 7, 17, 64, 853513, 8, 69, 3882809, 3, 11957417, 11, 19, 1280, 100146415, 5, 2593, 838216959, 1, 6205, 1536, 55, 13379363737, 53872
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OFFSET

1,17


COMMENTS

First edition of Washington incorrectly gives a(44) = h(Q(zeta_59)) = 41421. [Matthew Johnson, Jul 20 2013]


REFERENCES

L. C. Washington, Introduction to Cyclotomic Fields, Springer, pp. 353360.


LINKS

Table of n, a(n) for n=1..68.


FORMULA

a(n) = A061653(A042965(n+1)).  M. F. Hasler, Feb 04 2009


EXAMPLE

n=17: the 17th number not == 2 mod 4 is 23, and Q(zeta_23) = 3 is the first time that h is bigger than 1, so a(17) = 3.


CROSSREFS

Cf. A035115, A055513, A061653, A042965.
Sequence in context: A147989 A119329 A054724 * A141901 A200473 A180172
Adjacent sequences: A061491 A061492 A061493 * A061495 A061496 A061497


KEYWORD

nonn,nice


AUTHOR

N. J. A. Sloane, Jun 16 2001


EXTENSIONS

Missing term a(1) = 1 inserted by N. J. A. Sloane, Feb 05 2009 at the suggestion of Tanya Khovanova and M. F. Hasler
More terms (from bfile of A061653), Joerg Arndt, Oct 07 2012
a(44) corrected by Matthew Johnson, Jul 20 2013


STATUS

approved



