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%I #19 Dec 25 2018 17:27:21
%S 191,263,607,631,727,1019,1451,1499,1667,1907,2131,2143,2371,2659,
%T 2963,3083,3691,4003,4507,4643,5347,5419,5779,6619,7243,7963,9547,
%U 9739,11467,11587,11827,11923,12043,14347,15787,16963,20563
%N Discriminants of imaginary quadratic fields with class number 13 (negated).
%H Steven Arno, M. L. Robinson, Ferrell S. Wheeler, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa83/aa8341.pdf">Imaginary quadratic fields with small odd class number</a>, Acta Arith. 83 (1998) 295-330.
%H Duncan A. Buell, <a href="https://dx.doi.org/10.1090/S0025-5718-1977-0439802-X">Small class numbers and extreme values of L-functions of quadratic fields</a>, Math. Comp., 31 (1977), 786-796.
%H Keith Matthews, <a href="http://www.numbertheory.org/classnos/">Tables of imaginary quadratic fields with small class numbers</a>
%H C. Wagner, <a href="https://dx.doi.org/10.1090/S0025-5718-96-00722-3">Class Number 5, 6 and 7</a>, Math. Comput. 65, 785-800, 1996.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ClassNumber.html">Class Number.</a>
%H <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a>
%t Reap[ For[n = 1, n < 21000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 13, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* _Jean-François Alcover_, Oct 05 2012 *)
%Y Cf. A006203, A013658, A014602, A014603, A046002-A046020.
%K nonn,fini,full
%O 1,1
%A _Eric W. Weisstein_