cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A048925 Discriminants of imaginary quadratic fields with class number 24 (negated).

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%I A048925 #24 Feb 16 2025 08:32:40
%S A048925 695,759,1191,1316,1351,1407,1615,1704,1736,1743,1988,2168,2184,2219,
%T A048925 2372,2408,2479,2660,2696,2820,2824,2852,2856,2915,2964,3059,3064,
%U A048925 3127,3128,3444,3540,3560,3604,3620,3720,3864,3876,3891,3899,3912
%N A048925 Discriminants of imaginary quadratic fields with class number 24 (negated).
%H A048925 Andy Huchala, <a href="/A048925/b048925.txt">Table of n, a(n) for n = 0..510</a> (first 40 terms from Eric Weisstein)
%H A048925 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ClassNumber.html">Class Number.</a>
%H A048925 <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a>
%t A048925 Reap[ For[n = 1, n < 4000, n++, s = Sqrt[-n]; If[ NumberFieldClassNumber[s] == 24, d = -NumberFieldDiscriminant[s]; Print[d]; Sow[d]]]][[2, 1]] // Union (* _Jean-François Alcover_, Oct 05 2012 *)
%o A048925 (Sage)
%o A048925 ls = [(QuadraticField(-n, 'a').discriminant(),QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)];
%o A048925 [-a[0] for a in ls if a[1] == 24] # _Andy Huchala_, Feb 15 2022
%Y A048925 Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125.
%K A048925 nonn,fini,full
%O A048925 0,1
%A A048925 _Eric W. Weisstein_