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.
%I A076498 #13 Apr 07 2025 09:52:12 %S A076498 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,1,3,1,1,1,1,1,1,1,1,1, %T A076498 1,1,1,5,1,1,1,1,1,1,1,1,1,1,1,7,1,1,1,1,1,1,1,1,1,1,1,3,1,3,1,1,1,1, %U A076498 1,1,1,1,1,1,1,1,1,1,1,1 %N A076498 Class number h(p) of real quadratic field Q(sqrt(p)) where p is n-th prime == 1 mod 4. %H A076498 Herman te Riele and Hugh Williams, <a href="https://doi.org/10.1080/10586458.2003.10504715">New computations concerning the Cohen-Lenstra heuristics</a>, Experiment. Math. 12 (2003), no. 1, 99-113; <a href="https://projecteuclid.org/journals/experimental-mathematics/volume-12/issue-1/New-Computations-Concerning-the-Cohen-Lenstra-Heuristics/em/1064858787.full?tab=ArticleLink">alternative link</a>. %e A076498 h(p) = 1 for p < 229, h(229) = h(257) = h(733) = h(761) = 3, h(401) = 5 and h(577) = 7, ... %Y A076498 Cf. A002144, A003649, A076499. %K A076498 nonn %O A076498 1,22 %A A076498 _N. J. A. Sloane_, Nov 11 2002