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 A069913 #11 Aug 20 2021 00:21:24
%S A069913 0,1,2,5,4,11,6,16,12,19,10,37,12,27,26,42,16,54,18,59,36,43,22,100,
%T A069913 32,51,48,81,28,113,30,99,56,67,54,162,36,75,66,152,40,153,42,125,108,
%U A069913 91,46,240,60,134,86,147,52,202,82,204,96,115,58,331,60,123,144,219,96
%N A069913 a(n) = Sum_{d|n} (d-1)*tau(n/d).
%F A069913 a(n) = A007429(n) - A007425(n).
%F A069913 G.f.: Sum_{k>=1} tau(k) * x^(2*k) / (1 - x^k)^2. - _Ilya Gutkovskiy_, Aug 19 2021
%t A069913 Table[DivisorSum[n,(#-1)DivisorSigma[0,n/#]&],{n,100}] (* _Giorgos Kalogeropoulos_, Aug 19 2021 *)
%o A069913 (PARI) a(n) = sumdiv(n, d, (d-1)*numdiv(n/d)) \\ _Michel Marcus_, Jun 17 2013
%Y A069913 Cf. A000005, A006579, A007425, A007429.
%K A069913 nonn
%O A069913 1,3
%A A069913 _Vladeta Jovovic_, May 04 2002