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 A235872 #16 Nov 13 2022 08:39:39
%S A235872 1,2,1,4,1,2,1,8,9,2,1,4,1,2,1,16,1,18,1,4,1,2,1,8,25,2,9,4,1,2,1,32,
%T A235872 1,2,1,36,1,2,1,8,1,2,1,4,9,2,1,16,49,50,1,4,1,18,1,8,1,2,1,4,1,2,9,
%U A235872 64,1,2,1,4,1,2,1,72,1,2,25,4,1,2,1,16,81,2
%N A235872 Number of solutions to the equation x^2=0 in the ring of Gaussian integers modulo n.
%C A235872 Numbers of solutions to x^2 == y^2 (mod n), 2*x*y == 0 (mod n). - _Andrew Howroyd_, Aug 06 2018
%H A235872 Andrew Howroyd, <a href="/A235872/b235872.txt">Table of n, a(n) for n = 1..10000</a>
%F A235872 Multiplicative with a(2^e) = 2^e, a(p^e) = p^(2*floor(e/2)). - _Andrew Howroyd_, Aug 06 2018
%F A235872 Sum_{k=1..n} a(k) ~ c * n^(3/2), where c = (2/21)*(3+sqrt(2))*zeta(3/2)/zeta(3) = 0.91363892007.... - _Amiram Eldar_, Nov 13 2022
%t A235872 invoG[n_] := invoG[n] = Sum[If[Mod[(x + I y)^2, n] == 0, 1, 0], {x, 0, n - 1}, {y, 0, n - 1}]; Table[invoG[n], {n, 1, 104}]
%t A235872 f[p_, e_] := p^(2*Floor[e/2]); f[2, e_] := 2^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Nov 13 2022 *)
%o A235872 (PARI) a(n)={sum(i=0, n-1, sum(j=0, n-1, (i^2 - j^2)%n == 0 && 2*i*j%n == 0))} \\ _Andrew Howroyd_, Aug 06 2018
%o A235872 (PARI) a(n)={my(f=factor(n)); prod(i=1, #f~, my([p,e]=f[i,]); p^if(p==2, e, e - e%2))} \\ _Andrew Howroyd_, Aug 06 2018
%Y A235872 Cf. A062803, A090699.
%K A235872 nonn,mult
%O A235872 1,2
%A A235872 _José María Grau Ribas_, Apr 03 2014