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 A281572 #5 Jan 24 2017 20:29:51
%S A281572 1,3,6,11,18,30,45,68,98,139,192,266,357,478,632,828,1074,1386,1769,
%T A281572 2250,2840,3566,4452,5534,6842,8427,10335,12624,15361,18634,22519,
%U A281572 27137,32598,39047,46645,55580,66050,78313,92630,109330,128760,151342,177517,207833,242878,283326,329944,383598,445246,516013
%N A281572 Expansion of Sum_{i>=1} mu(i)^2*x^i/(1 - x^i) / Product_{j>=1} (1 - mu(j)^2*x^j), where mu() is the Moebius function (A008683).
%C A281572 Total number of parts in all partitions of n into squarefree parts (A005117).
%C A281572 Convolution of A034444 and A073576.
%H A281572 <a href="/index/Par#partN">Index entries for related partition-counting sequences</a>
%F A281572 G.f.: Sum_{i>=1} mu(i)^2*x^i/(1 - x^i) / Product_{j>=1} (1 - mu(j)^2*x^j).
%e A281572 a(4) = 11 because we have [3, 1], [2, 2], [2, 1, 1], [1, 1, 1, 1] and 2 + 2 + 3 + 4 = 11.
%t A281572 nmax = 50; Rest[CoefficientList[Series[Sum[MoebiusMu[i]^2 x^i/(1 - x^i), {i, 1, nmax}]/Product[1 - MoebiusMu[j]^2 x^j, {j, 1, nmax}], {x, 0, nmax}], x]]
%Y A281572 Cf. A005117, A008683, A034444, A073576.
%K A281572 nonn
%O A281572 1,2
%A A281572 _Ilya Gutkovskiy_, Jan 24 2017