The On-Line Encyclopedia of Integer Sequences (OEIS)

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A123563

Discriminants of imaginary quadratic fields with class number 20 (negated).
(history; published version)

#9 by Charles R Greathouse IV at Sun Feb 16 08:33:03 EST 2025

LINKS

Eric Weisstein's World of Mathematics, <a href="httphttps://mathworld.wolfram.com/ClassNumber.html">Class Number.</a>

Discussion

Sun Feb 16

08:33

OEIS Server: https://oeis.org/edit/global/3014

#8 by R. J. Mathar at Fri Jan 11 16:29:50 EST 2013

STATUS

editing

approved

#7 by R. J. Mathar at Fri Jan 11 16:29:45 EST 2013

LINKS

Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ClassNumber.html">Link to a section of The World of MathematicsClass Number.</a>

STATUS

approved

editing

#6 by T. D. Noe at Fri Oct 05 11:27:26 EDT 2012

STATUS

proposed

approved

#5 by Jean-François Alcover at Fri Oct 05 09:42:18 EDT 2012

STATUS

editing

proposed

#4 by Jean-François Alcover at Fri Oct 05 09:42:13 EDT 2012

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 *)

STATUS

approved

editing

#3 by Russ Cox at Sat Mar 31 12:39:11 EDT 2012

AUTHOR

_Eric W. Weisstein (eric(AT)weisstein.com), _, Nov 19 2006

Discussion

Sat Mar 31

12:39

OEIS Server: https://oeis.org/edit/global/877

#2 by N. J. A. Sloane at Sun Jun 29 03:00:00 EDT 2008

LINKS

E. W. Eric Weisstein, 's World of Mathematics, <a href="http://mathworld.wolfram.com/ClassNumber.html">Link to a section of The World of Mathematics.</a>

KEYWORD

nonn,fini,new

AUTHOR

Eric W. Weisstein (eric(AT)weisstein.com), Nov 19 2006

#1 by N. J. A. Sloane at Wed Dec 06 03:00:00 EST 2006

NAME

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

DATA

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

OFFSET

1,1

COMMENTS

A finite sequence with exactly 350 terms.

LINKS

E. W. Weisstein, <a href="http://mathworld.wolfram.com/ClassNumber.html">Link to a section of The World of Mathematics.</a>

CROSSREFS

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

KEYWORD

nonn,fini,new

AUTHOR

Eric W. Weisstein (eric(AT)weisstein.com), Nov 19 2006

STATUS

approved