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 A359186 #18 Aug 27 2023 17:03:18
%S A359186 1,9,49,265,1281,6201,28673,131337,589873,2622729,11534337,50338105,
%T A359186 218103809,939552777,4026533169,17180000521,73014444033,309238241337,
%U A359186 1305670057985,5497560761865,23089744212017,96757034778633,404620279021569,1688849910733113
%N A359186 a(n) = Sum_{d|n} d * 4^(d-1).
%F A359186 G.f.: Sum_{k>=1} x^k/(1 - 4 * x^k)^2.
%t A359186 a[n_] := DivisorSum[n, 4^(#-1)*# &]; Array[a, 24] (* _Amiram Eldar_, Aug 27 2023 *)
%o A359186 (PARI) a(n) = sumdiv(n, d, d*4^(d-1));
%o A359186 (PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-4*x^k)^2))
%Y A359186 Cf. A002129, A083413, A359018.
%Y A359186 Cf. A167531, A339684, A359190.
%K A359186 nonn,easy
%O A359186 1,2
%A A359186 _Seiichi Manyama_, Dec 19 2022