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 A373039 #10 Jan 08 2025 09:27:11
%S A373039 0,1,27,257,1625,6508,24010,65793,177174,391626,893101,1665644,
%T A373039 3398759,5786411,10531652,16843009,29065308,42698935,70764303,
%U A373039 100231882,155608837,215237342,326294606,426404460,634767250,819100920,1162438641,1480961067,2084357107,2538128133
%N A373039 a(n) = (A372966(n) - 1)/240.
%H A373039 Amiram Eldar, <a href="/A373039/b373039.txt">Table of n, a(n) for n = 1..10000</a>
%F A373039 From _Amiram Eldar_, Jan 08 2025: (Start)
%F A373039 Dirichlet g.f.: zeta(s) * (zeta(s-8)/zeta(s-4) - 1)/240.
%F A373039 Sum_{k=1..n} a(k) ~ c * n^9, where c = zeta(9)/(2160*zeta(5)) = 0.000447372... . (End)
%t A373039 f[p_, e_] := (p^(8*e + 4) + 1)/(p^4 + 1); a[1] = 0; a[n_] := (Times @@ f @@@ FactorInteger[n] - 1) / 240; Array[a, 30] (* _Amiram Eldar_, Jan 08 2025 *)
%o A373039 (PARI) a(n) = (sigma(n^2, 8)/sigma(n^2, 4)-1)/240
%Y A373039 Cf. A000290, A001159, A013956.
%K A373039 nonn
%O A373039 1,3
%A A373039 _Hugo Pfoertner_, May 20 2024