A123563 - OEIS

A123563

Discriminants of imaginary quadratic fields with class number 20 (negated).

455, 615, 776, 824, 836, 920, 1064, 1124, 1160, 1263, 1284, 1460, 1495, 1524, 1544, 1592, 1604, 1652, 1695, 1739, 1748, 1796, 1880, 1887, 1896, 1928, 1940, 1956, 2136, 2247, 2360, 2404, 2407, 2483, 2487, 2532, 2552

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OFFSET

1,1

COMMENTS

A finite sequence with exactly 350 terms.

LINKS

Table of n, a(n) for n=1..37.

Eric Weisstein's World of Mathematics, Class Number.

MATHEMATICA

Reap[ For[n = 1, n < 3000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 20, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* Jean-François Alcover, Oct 05 2012 *)

CROSSREFS

Cf. A006203, A013658, A014602, A014603, A046002, ..., A046016, A046018, A046020.

Sequence in context: A232758 A284430 A206338 * A043475 A324633 A260735

Adjacent sequences: A123560 A123561 A123562 * A123564 A123565 A123566

KEYWORD

nonn,fini,changed

AUTHOR

Eric W. Weisstein, Nov 19 2006

STATUS

approved