%I A006203 M5131
%S A006203 23,31,59,83,107,139,211,283,307,331,379,499,547,643,883,907
%N A006203 Discriminants of imaginary quadratic fields with class number 3 (negated).
%C A006203 Also n such that Q(sqrt(-n)) has class number 3.
%D A006203 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006203 H. Cohen, Course in Computational Alg. No. Theory, Springer, 1993, p. 
               514.
%D A006203 J. M. Masley, Where are the number fields with small class number?, pp. 
               221-242 of Number Theory Carbondale 1979, Lect. Notes Math. 751 (1982).
%D A006203 Heegner K., 1952. Diophantische Analysis und Modulfunktionen. Matematische 
               Zaitschrift Vol. 56. p. 253. [From Artur Jasinski (grafix(AT)csl.pl), 
               Oct 21 2008]
%H A006203 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               ClassNumber.html">Link to a section of The World of Mathematics.</
               a>
%H A006203 <a href="Sindx_Qua.html#quadfield">Index entries for sequences related 
               to quadratic fields</a>
%o A006203 For PARI code see A005847.
%Y A006203 Cf. A013658, A014602, A014603, A046002, ..., A046020. Cf. also A003173, 
               A005847, ...
%Y A006203 Sequence in context: A064792 A030670 A030680 this_sequence A153635 A052160 
               A165985
%Y A006203 Adjacent sequences: A006200 A006201 A006202 this_sequence A006204 A006205 
               A006206
%K A006203 fini,nonn,full,nice
%O A006203 1,1
%A A006203 N. J. A. Sloane (njas(AT)research.att.com).