This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A296818 #30 Jun 17 2022 13:06:08
%S A296818 -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 A296818 73,85
%N A296818 Squarefree values of k for which the quadratic field Q[ sqrt(k) ] possesses a norm-Euclidean ideal class.
%C A296818 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 A296818 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 A296818 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 A296818 -5 is in the sequence because the ideal (2, 1+sqrt(-5)) is norm-Euclidean in the number field Q[ sqrt(-5) ].
%Y A296818 Cf. A003174, A048981.
%K A296818 fini,sign,full,nice
%O A296818 1,1
%A A296818 _Robert C. Lyons_, Dec 22 2017