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 A307075 #5 Mar 23 2019 12:38:47
%S A307075 1,1,4,15,47,160,517,1721,5668,18687,61687,203448,671253,2214377,
%T A307075 7305308,24100319,79506903,262294336,865310405,2854666385,9417565852,
%U A307075 31068622271,102495625503,338133855032,1115506197957,3680063534409,12140557957708,40051794232519,132131177728807
%N A307075 Expansion of 1/(1 - Sum_{k>=1} mu(k)*x^k*(1 + x^k)/(1 - x^k)^3).
%C A307075 Invert transform of A007434.
%F A307075 a(0) = 1; a(n) = Sum_{k=1..n} A007434(k)*a(n-k).
%t A307075 nmax = 28; CoefficientList[Series[1/(1 - Sum[MoebiusMu[k] x^k (1 + x^k)/(1 - x^k)^3, {k, 1, nmax}]), {x, 0, nmax}], x]
%t A307075 a[0] = 1; a[n_] := a[n] = Sum[Sum[MoebiusMu[k/d] d^2, {d, Divisors[k]}] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 28}]
%Y A307075 Cf. A007434, A008683, A159929, A301875, A301876.
%K A307075 nonn
%O A307075 0,3
%A A307075 _Ilya Gutkovskiy_, Mar 22 2019