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 A046020 Discriminants of imaginary quadratic fields with class number 23 (negated). 28
 647, 1039, 1103, 1279, 1447, 1471, 1811, 1979, 2411, 2671, 3491, 3539, 3847, 3923, 4211, 4783, 5387, 5507, 5531, 6563, 6659, 6703, 7043, 9587, 9931, 10867, 10883, 12203, 12739, 13099, 13187, 15307, 15451, 16267, 17203, 17851, 18379, 20323 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Giovanni Resta, Table of n, a(n) for n = 1..68 (full sequence, from Steven Arno et al.) Steven Arno, M. L. Robinson, Ferrell S. Wheeler, Imaginary quadratic fields with small odd class number, Acta Arith. 83 (1998) 295-330. Duncan A. Buell, Small class numbers and extreme values of L-functions of quadratic fields, Math. Comp., 31 (1977), 786-796. Keith Matthews, Tables of imaginary quadratic fields with small class numbers C. Wagner, Class Number 5, 6 and 7, Math. Comput. 65, 785-800, 1996. Eric Weisstein's World of Mathematics, Class Number. MATHEMATICA Reap[ Do[ If[ NumberFieldClassNumber[ Sqrt[-n] ] == 23, d = -NumberFieldDiscriminant[ Sqrt[-n] ]; Print[d]; Sow[d]], {n, 1, 21000}]][[2, 1]] // Union (* Jean-François Alcover, Oct 22 2012 *) PROG (PARI) select(n->qfbclassno(-n)==23, vector(22696, n, 4*n+3)) \\ Charles R Greathouse IV, Apr 25 2013 CROSSREFS Cf. A006203, A013658, A014602, A014603, A046002-A046020. Sequence in context: A228575 A250989 A187434 * A108821 A035885 A114827 Adjacent sequences:  A046017 A046018 A046019 * A046021 A046022 A046023 KEYWORD nonn,fini,full AUTHOR EXTENSIONS 68 discriminants in this sequence (proved). STATUS approved

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Last modified June 2 14:21 EDT 2020. Contains 334787 sequences. (Running on oeis4.)