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 A352555 #5 Mar 21 2022 11:10:50 %S A352555 1,0,1,1,2,0,1,0,2,0,0,1,0,0,2,2,2,0,0,2,1,0,0,0,5,0,3,1,0,0,0,0,0,0, %T A352555 2,2,2,0,0,0,2,0,2,0,4,0,2,2,2,0,2,0,0,0,0,0,0,0,2,2,0,0,2,3,0,0,2,2, %U A352555 0,0,0,0,0,0,5,0,0,0,2,4,5,0,2,1,4,0,0,0,2,0,0,0,0,0,0,0,0,0,0,5,2,0,0,0,2,0,0,3,2,0,2,2,0,0,0,0,0,0 %N A352555 a(n) = number of modules with n elements over the ring of integers in the real quadratic field of discriminant 21. %C A352555 See A352550 for comments and PARI code. %Y A352555 Cf. A038540, A038541, A248107, A352550-A352567. %K A352555 nonn %O A352555 1,5 %A A352555 _N. J. A. Sloane_, Mar 20 2022