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 A119526 #4 Sep 12 2016 18:22:20
%S A119526 1,1,3,35,45045,4512611027925,2052546673789621992207225,
%T A119526 104326219460917277964091790659689347988584942875383375,
%U A119526 65134729714436885436168002936626505274493455112928327538888490982573786624726691153873697518277375333357875
%N A119526 Odd denominators of n * n-th harmonic number = A027611[2^n].
%C A119526 The next term (a(9)) has 218 digits. - _Harvey P. Dale_, Sep 12 2016
%F A119526 a(n) = Denominator[2^n*Sum[1/k,{k,1,2^n}]]. a(n) = A027611[2^n].
%t A119526 Denominator[Table[2^n*Sum[1/k,{k,1,2^n}],{n,0,10}]]
%t A119526 With[{nn=300},Select[Denominator[Times@@@Thread[{Range[nn],HarmonicNumber[Range[nn]]}]],OddQ]] (* _Harvey P. Dale_, Sep 12 2016 *)
%Y A119526 Cf. A027611.
%K A119526 frac,nonn
%O A119526 0,3
%A A119526 _Alexander Adamchuk_, Jul 27 2006