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Squarefree values of k for which the quadratic field Q[ sqrt(k) ] possesses a norm-Euclidean ideal class.
2

%I #30 Jun 17 2022 13:06:08

%S -15,-11,-7,-5,-3,-2,-1,2,3,5,6,7,10,11,13,15,17,19,21,29,33,37,41,57,

%T 73,85

%N Squarefree values of k for which the quadratic field Q[ sqrt(k) ] possesses a norm-Euclidean ideal class.

%C This generalizes A048981, because the unit ideal of a norm-Euclidean number field is a norm-Euclidean ideal. In other words, this sequence is the union of {-15, -5, 10, 15, 85} and A048981.

%H Kelly Emmrich and Clark Lyons, <a href="https://wcnt.files.wordpress.com/2017/12/wcnt2017-kellyclark.pdf">Norm-Euclidean Ideals in Galois Cubic Fields</a>, Slides, West Coast Number Theory, Dec 18 2017.

%H H. W. Lenstra, Jr., <a href="https://www.math.leidenuniv.nl/~hwl/PUBLICATIONS/1979c/art.pdf">Euclidean ideal classes</a>, Soc. Math. France Astérisque, 1979, pp. 121-131.

%e -5 is in the sequence because the ideal (2, 1+sqrt(-5)) is norm-Euclidean in the number field Q[ sqrt(-5) ].

%Y Cf. A003174, A048981.

%K fini,sign,full,nice

%O 1,1

%A _Robert C. Lyons_, Dec 22 2017