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 A019321 #17 Feb 26 2024 09:16:58
%S A019321 3,2,4,13,10,121,7,1093,82,757,61,88573,73,797161,547,4561,6562,
%T A019321 64570081,703,581130733,5905,368089,44287,47071589413,6481,3501192601,
%U A019321 398581,387440173,478297,34315188682441,8401,308836698141973,43046722,2413941289,32285041
%N A019321 Cyclotomic polynomials at x=3.
%H A019321 Paolo Xausa, <a href="/A019321/b019321.txt">Table of n, a(n) for n = 0..1000</a>
%H A019321 <a href="/index/Cy#CyclotomicPolynomialsValuesAtX">Index entries for cyclotomic polynomials, values at X</a>
%p A019321 with(numtheory,cyclotomic); f := n->subs(x=3,cyclotomic(n,x)); seq(f(i),i=0..64);
%t A019321 Join[{3}, Cyclotomic[Range[50], 3]] (* _Paolo Xausa_, Feb 26 2024 *)
%K A019321 nonn
%O A019321 0,1
%A A019321 _Simon Plouffe_