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 A380784 #14 Feb 17 2025 03:34:50 %S A380784 2,3,5,7,11,13,17,19,23,29,31,37,41,43,61,67,71 %N A380784 Prime numbers p where the cyclotomic field Q(zeta_(p-1)) has class number one. %C A380784 For a prime number p, the cyclotomic field of power p-1 can take a significant part in Z/pZ or p-adic field Q_p, since 1~p-1 are all (p-1)-th unit roots in Z/pZ. It would be much better if the cyclotomic integer ring is a unique factorization domain. %C A380784 A prime number p is in this sequence if and only if (p-1)/2 is in A005848 (if p equals 3 modulus 4) or p-1 is in A005848 (otherwise). %Y A380784 Cf. A005848. %K A380784 nonn,fini,full %O A380784 1,1 %A A380784 _Steven Lu_, Feb 02 2025