A003174 - OEIS

A003174

Positive integers D such that Q[sqrt(D)] is a quadratic field which is norm-Euclidean.
(Formerly M0619)

2, 3, 5, 6, 7, 11, 13, 17, 19, 21, 29, 33, 37, 41, 57, 73

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OFFSET

1,1

COMMENTS

These integers yield norm-Euclidean real quadratic fields. There are other positive integers, e.g., D=14 or D=69, for which Q[sqrt(D)] is Euclidean, but for a Euclidean function different from the field norm.

For further references see sequence A048981 which also lists negative D corresponding to (complex) norm-Euclidean fields. - M. F. Hasler, Jan 26 2014

REFERENCES

H. Cohn, A Second Course in Number Theory, Wiley, NY, 1962, p. 109.

G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 213.

K. Inkeri, Über den Euklidischen Algorithmus in quadratischen Zahlkörpern. Ann. Acad. Sci. Fennicae Ser. A. 1. Math.-Phys., No. 41, 1-35, 1947. [Incorrectly gives 97 as a member of this sequence.]

W. J. LeVeque, Topics in Number Theory. Addison-Wesley, Reading, MA, 2 vols., 1956, Vol. 2, p. 57.

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

H. M. Stark, An Introduction to Number Theory. Markham, Chicago, 1970, p. 294.

LINKS

Table of n, a(n) for n=1..16.

H. Chatland and H. Davenport, Euclid's algorithm in real quadratic fields, Canadian J. Math. 2, (1950), 289-296.

S. R. Finch, Class number theory [Cached copy, with permission of the author]

Pierre Samuel, Unique factorization, Amer. Math. Monthly 75 (1968), 945-952.

Index entries for sequences related to quadratic fields

FORMULA

a(n) = A048981(n+5). - M. F. Hasler, Jan 26 2014

PROG