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 A352550 #28 Nov 24 2023 21:17:00 %S A352550 1,0,0,1,1,0,0,0,1,0,2,0,0,0,0,2,0,0,2,1,0,0,0,0,2,0,0,0,2,0,2,0,0,0, %T A352550 0,1,0,0,0,0,2,0,0,2,1,0,0,0,1,0,0,0,0,0,2,0,0,0,2,0,2,0,0,3,0,0,0,0, %U A352550 0,0,2,0,0,0,0,2,0,0,2,2,2,0,0,0,0,0,0,0,2,0,0,0,0,0,2 %N A352550 a(n) = number of modules with n elements over the ring of integers in the real quadratic field of discriminant 5. %H A352550 Don Zagier, <a href="/A352550/a352550.txt">On the Number of n-Element Modules Over the Ring of Integers in a Quadratic Number Field</a> [Based on email to N. J. A. Sloane, March 18 2022] %o A352550 (PARI) \\ Don Zagier, Mar 18 2022 %o A352550 PZ(D,m=20) = Z=dirmul(vector(m,n,1),vD=vector(m,n,kronecker(D,n))); v=Z; \ %o A352550 for(j=2,log(m)/log(2), V=v*0;for(k=1,m^(1/j),V[k^j]=Z[k]);v=dirmul(v,V)); v %o A352550 PZ(5,100) %Y A352550 Cf. A038540, A038541, A248107, A352551-A352567. %K A352550 nonn %O A352550 1,11 %A A352550 _N. J. A. Sloane_, Mar 20 2022