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A005474 Class numbers of quadratic fields.
(Formerly M2215)
0
1, 1, 1, 1, 1, 3, 1, 3, 5, 3, 3, 7, 3, 5, 7, 3, 3, 5, 9, 7, 3, 5, 5, 15, 9, 19, 5, 13, 9, 9, 5, 19, 9, 5, 7, 15, 13, 9, 9, 15, 25, 13, 9, 27, 19, 15, 21, 7, 13, 11, 23, 9, 13, 13, 11, 33, 15, 25, 23, 15, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..61.

D. Shanks, The simplest cubic fields, Math. Comp., 28 (1974), 1137-1152.

Index entries for sequences related to quadratic fields

CROSSREFS

Sequence in context: A110091 A263051 A284130 * A012264 A063198 A122582

Adjacent sequences:  A005471 A005472 A005473 * A005475 A005476 A005477

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 13 04:20 EST 2019. Contains 329085 sequences. (Running on oeis4.)