A046018 Discriminants of imaginary quadratic fields with class number 21 (negated).

431, 503, 743, 863, 1931, 2503, 2579, 2767, 2819, 3011, 3371, 4283, 4523, 4691, 5011, 5647, 5851, 5867, 6323, 6691, 7907, 8059, 8123, 8171, 8243, 8387, 8627, 8747, 9091, 9187, 9811, 9859, 10067, 10771, 11731, 12107, 12547, 13171, 13291

Offset

1,1

Comments

85 discriminants in this sequence (proved).

Links

Giovanni Resta, Table of n, a(n) for n = 1..85 (full sequence, from Weisstein's World of Mathematics)

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[ For[n = 1, n < 14000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 21, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* Jean-François Alcover, Oct 05 2012 *)

Crossrefs

Cf. A006203, A013658, A014602, A014603, A046002 - A046020.

Sequence in context: A160518 A273807 A323047 * A142802 A003548 A179173

Adjacent sequences: A046015 A046016 A046017 * A046019 A046020 A046021

Keyword

nonn,fini,full

Author

Eric W. Weisstein

Status

approved