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 A035183 #22 Nov 20 2023 11:53:01
%S A035183 1,0,2,1,1,0,2,0,3,0,0,2,0,0,2,1,0,0,0,1,4,0,2,0,1,0,4,2,2,0,0,0,0,0,
%T A035183 2,3,0,0,0,0,2,0,2,0,3,0,2,2,3,0,0,0,0,0,0,0,0,0,0,2,2,0,6,1,0,0,2,0,
%U A035183 4,0,0,0,0,0,2,0,0,0,0,1,5
%N A035183 Coefficients in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s)+Kronecker(m,p)*p^(-2s))^(-1) for m = -5.
%H A035183 G. C. Greubel, <a href="/A035183/b035183.txt">Table of n, a(n) for n = 1..10000</a>
%F A035183 From _Amiram Eldar_, Oct 17 2022: (Start)
%F A035183 a(n) = Sum_{d|n} Kronecker(-5, d).
%F A035183 Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2*Pi/(3*sqrt(5)) = 0.936641... . (End)
%F A035183 Multiplicative with a(5^e) = 1, a(p^e) = (1+(-1)^e)/2 if Kronecker(-5, p) = -1 (p is in A296923), and a(p^e) = e+1 if Kronecker(-5, p) = 1 (p is in A139513). - _Amiram Eldar_, Nov 20 2023
%t A035183 a[n_] := If[n < 0, 0, DivisorSum[n, KroneckerSymbol[-5, #] &]]; Table[ a[n], {n, 1, 100}] (* _G. C. Greubel_, Apr 27 2018 *)
%o A035183 (PARI) my(m=-5); direuler(p=2,101,1/(1-(kronecker(m,p)*(X-X^2))-X))
%o A035183 (PARI) a(n) = sumdiv(n, d, kronecker(-5, d)); \\ _Michel Marcus_, Oct 07 2023
%Y A035183 Cf. A139513, A296923.
%K A035183 nonn,easy,mult
%O A035183 1,3
%A A035183 _N. J. A. Sloane_