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 A344480 #9 Mar 31 2025 14:03:54
%S A344480 1,11,85,1103,15631,284795,5764809,134745175,3486961642,100097682141,
%T A344480 3138428376733,107019534806039,3937376385699303,155577590686826319,
%U A344480 6568408813691811835,295152408847835466855,14063084452067724991027,708238048886862707907062,37589973457545958193355621,2097154000001929438984022793
%N A344480 a(n) = Sum_{d|n} d * sigma_d(d), where sigma_k(n) is the sum of the k-th powers of the divisors of n.
%C A344480 If p is prime, a(p) = Sum_{d|p} d * sigma_d(d) = 1*(1^1) + p*(1^p + p^p) = 1 + p + p^(p+1).
%C A344480 Inverse Möbius transform of n * sigma_n(n). - _Wesley Ivan Hurt_, Mar 31 2025
%e A344480 a(6) = Sum_{d|6} d * sigma_d(d) = 1*(1^1) + 2*(1^2 + 2^2) + 3*(1^3 + 3^3) + 6*(1^6 + 2^6 + 3^6 + 6^6) = 284795.
%t A344480 Table[Sum[k*DivisorSigma[k, k] (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 30}]
%o A344480 (PARI) a(n) = sumdiv(n, d, d*sigma(d, d)); \\ _Michel Marcus_, May 21 2021
%Y A344480 Cf. A245466, A321141, A334874, A343781, A344434.
%K A344480 nonn
%O A344480 1,2
%A A344480 _Wesley Ivan Hurt_, May 20 2021