A046020 - OEIS

A046020

Discriminants of imaginary quadratic fields with class number 23 (negated).

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

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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.

Index entries for sequences related to quadratic fields

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 A345702 A035885

Adjacent sequences: A046017 A046018 A046019 * A046021 A046022 A046023

KEYWORD

nonn,fini,full

AUTHOR

Eric W. Weisstein

EXTENSIONS

68 discriminants in this sequence (proved).

STATUS

approved