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 A014603 #38 Feb 16 2025 08:32:33
%S A014603 15,20,24,35,40,51,52,88,91,115,123,148,187,232,235,267,403,427
%N A014603 Discriminants of imaginary quadratic fields with class number 2 (negated).
%C A014603 Includes only fundamental discriminants. The list of non-fundamental imaginary quadratic discriminants with class number 2 (negated) is 32, 36, 48, 60, 64, 72, 75, 99, 100, 112, 147. - _Andrew V. Sutherland_, Apr 08 2010
%D A014603 H. Cohen, Course in Computational Alg. No. Theory, Springer, 1993, p. 229.
%H A014603 A. Abatzoglou, A. Silverberg, A. V. Sutherland, A, Wong, <a href="http://arxiv.org/abs/1404.0107">A framework for deterministic primality proving using elliptic curves with complex multiplication</a>, arXiv:1404.0107 [math.NT], 2014.
%H A014603 Alexandre Gélin, Everett W. Howe, and Christophe Ritzenthaler, <a href="https://arxiv.org/abs/1806.03826">Principally Polarized Squares of Elliptic Curves with Field of Moduli Equal To Q</a>, arXiv:1806.03826 [math.NT], 2018 (see table 1 page 4).
%H A014603 Rick L. Shepherd, <a href="http://libres.uncg.edu/ir/uncg/f/Shepherd_uncg_0154M_11099.pdf">Binary quadratic forms and genus theory</a>, Master of Arts Thesis, University of North Carolina at Greensboro, 2013
%H A014603 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number.</a>
%H A014603 <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a>
%t A014603 Union[ (-NumberFieldDiscriminant[ Sqrt[-#]] &) /@ Select[ Range[500], NumberFieldClassNumber[ Sqrt[-#]] == 2 &]] (* _Jean-François Alcover_, Jan 04 2012 *)
%o A014603 (PARI) ok(n)={isfundamental(-n) && quadclassunit(-n).no == 2} \\ _Andrew Howroyd_, Jul 20 2018
%o A014603 (Sage) [n for n in (1..500) if is_fundamental_discriminant(-n) and QuadraticField(-n, 'a').class_number()==2] # _G. C. Greubel_, Mar 01 2019
%Y A014603 Cf. A006203, A013658, A014602, A046002, ..., A046020.
%Y A014603 Cf. A191410.
%K A014603 nonn,fini,full,nice
%O A014603 1,1
%A A014603 Eric Rains (rains(AT)caltech.edu)
%E A014603 Offset corrected by _Jianing Song_, Aug 29 2018