A373039 a(n) = (A372966(n) - 1)/240.
0, 1, 27, 257, 1625, 6508, 24010, 65793, 177174, 391626, 893101, 1665644, 3398759, 5786411, 10531652, 16843009, 29065308, 42698935, 70764303, 100231882, 155608837, 215237342, 326294606, 426404460, 634767250, 819100920, 1162438641, 1480961067, 2084357107, 2538128133
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
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 *)
-
PARI
a(n) = (sigma(n^2, 8)/sigma(n^2, 4)-1)/240
Formula
From Amiram Eldar, Jan 08 2025: (Start)
Dirichlet g.f.: zeta(s) * (zeta(s-8)/zeta(s-4) - 1)/240.
Sum_{k=1..n} a(k) ~ c * n^9, where c = zeta(9)/(2160*zeta(5)) = 0.000447372... . (End)