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A123563 Discriminants of imaginary quadratic fields with class number 20 (negated). 2
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 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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

AUTHOR

Eric W. Weisstein, Nov 19 2006

STATUS

approved

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)