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 A272428 #10 Aug 07 2019 22:13:58
%S A272428 0,1,1,3,13,71,461,3447,29093,272767,2797069,30897015,362691733,
%T A272428 4475707535,57612706973,769779683367,10648337804645,152377871778559,
%U A272428 2256813406989421,34636615303780503
%N A272428 Expansion of the continued fraction x/(1-pi(2)*x/(1-pi(3)*x/(1-pi(4)*x/(1-...)))).
%C A272428 The initial similarity with A233824 may explain that method's success in representing pi(n).
%H A272428 G. C. Greubel, <a href="/A272428/b272428.txt">Table of n, a(n) for n = 0..250</a>
%F A272428 G.f.: x/(1-pi(2)*x/(1-pi(3)*x/(1-pi(4)*x/(1-...)))) a continued fraction.
%t A272428 CoefficientList[Series[x/(1 + ContinuedFractionK[-x*PrimePi[k], 1, {k, 2, 60}]), {x,0, 60}], x]
%Y A272428 Cf. A000720, A233824.
%K A272428 nonn
%O A272428 0,4
%A A272428 _Benedict W. J. Irwin_, Apr 29 2016