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 A054601 #11 Mar 10 2021 09:26:39
%S A054601 0,1,2,7,8,21,38,71,128,277,522,1035,2072,4109,8206,16467,32768,65553,
%T A054601 131186,262163,524328,1048817,2097174,4194327,8388992,16777321,
%U A054601 33554458,67109695,134217784,268435485,536872638,1073741855,2147483648
%N A054601 a(n) = Sum_{d|n, d odd} d*2^(n/d - 1), a(0)=0.
%H A054601 Seiichi Manyama, <a href="/A054601/b054601.txt">Table of n, a(n) for n = 0..1000</a>
%F A054601 G.f.: Sum_{k>0} (1-(-1)^k)/2*k*x^k/(1-2*x^k). - _Vladeta Jovovic_, Oct 17 2003
%o A054601 (PARI) a(n) = if (n, sumdiv(n, d, if (d%2, d*2^(n/d - 1))), 0); \\ _Michel Marcus_, Mar 10 2021
%Y A054601 Cf. A054598, A054599, A054600, A000016, A000031.
%K A054601 nonn
%O A054601 0,3
%A A054601 _N. J. A. Sloane_, Apr 16 2000