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 A326812 #8 Oct 19 2019 21:01:28
%S A326812 1,1,4,1,1,4,8,1,4,1,1,4,1,8,19,1,1,4,1,1,11,1,1,4,1,1,4,8,1,19,32,1,
%T A326812 4,1,8,4,1,1,4,1,1,11,1,1,19,1,1,4,8,1,4,1,1,4,1,8,4,1,1,19,1,32,74,1,
%U A326812 1,4,1,1,4,8,1,4,1,1,19,1,8,4,1,1,4,1,1,11,1
%N A326812 Expansion of Sum_{k>=1} (2^k - 1) * x^(2^k - 1) / (1 - x^(2^k - 1)).
%C A326812 Sum of divisors of n of the form 2^j - 1 for j >= 1.
%F A326812 L.g.f.: -log(Product_{n>=1} (1 - x^(2^n - 1))) = Sum_{n>=1} a(n) * x^n / n.
%F A326812 exp(Sum_{n>=1} a(n) * x^n / n) = g.f. for A000929.
%F A326812 exp(Sum_{n>=1} (-1)^(n + 1) * a(n) * x^n / n) = g.f. for A079559.
%F A326812 a(n) = Sum_{d|n} A036987(d) * d.
%t A326812 nmax = 85; CoefficientList[Series[Sum[(2^k - 1) x^(2^k - 1)/(1 - x^(2^k - 1)), {k, 1, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x] // Rest
%t A326812 Table[Sum[Mod[CatalanNumber[d], 2] d, {d, Divisors[n]}], {n, 1, 85}]
%Y A326812 Cf. A000225, A000929, A036987, A038712, A079559, A154402, A161790 (positions of 1's).
%K A326812 nonn
%O A326812 1,3
%A A326812 _Ilya Gutkovskiy_, Oct 19 2019