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 A359811 #11 Jan 14 2023 08:44:23
%S A359811 1,3,5,13,17,53,65,177,293,625,1025,2541,4097,8769,17109,34561,65537,
%T A359811 136013,262145,534481,1054629,2110465,4194305,8449325,16787217,
%U A359811 33615873,67155845,134403521,268435457,537370845,1073741825,2148270081,4295327397,8591179777
%N A359811 a(n) = Sum_{d|n} 2^(d-1) * d^(n/d-1).
%F A359811 G.f.: Sum_{k>0} 2^(k-1) * x^k / (1 - k * x^k).
%F A359811 If p is prime, a(p) = 1 + 2^(p-1).
%F A359811 a(n) ~ 2^(n-1). - _Vaclav Kotesovec_, Jan 14 2023
%t A359811 Table[Sum[2^(d-1) * d^(n/d - 1), {d, Divisors[n]}], {n, 1, 40}] (* _Vaclav Kotesovec_, Jan 14 2023 *)
%o A359811 (PARI) a(n) = sumdiv(n, d, 2^(d-1)*d^(n/d-1));
%o A359811 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, 2^(k-1)*x^k/(1-k*x^k)))
%Y A359811 Cf. A087909, A359134, A359730, A359796.
%K A359811 nonn,easy
%O A359811 1,2
%A A359811 _Seiichi Manyama_, Jan 14 2023