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 A195577 #13 Dec 07 2016 10:27:28
%S A195577 1,4,56,299,1020,3180,3901,20944,272996,1465799,4993800,15577800,
%T A195577 19105801,102585004,1337133056,7179484499,24459629220,76300063380,
%U A195577 93580208101,502461329944,6549277433996,35165113611599,119803258923600
%N A195577 Denominators a(n) of Pythagorean approximations b(n)/a(n) to 3/5.
%C A195577 See A195500 for a discussion and references.
%t A195577 r = 3/5; z = 26;
%t A195577 p[{f_, n_}] := (#1[[2]]/#1[[
%t A195577 1]] &)[({2 #1[[1]] #1[[2]], #1[[1]]^2 - #1[[
%t A195577 2]]^2} &)[({Numerator[#1], Denominator[#1]} &)[
%t A195577 Array[FromContinuedFraction[
%t A195577 ContinuedFraction[(#1 + Sqrt[1 + #1^2] &)[f], #1]] &, {n}]]]];
%t A195577 {a, b} = ({Denominator[#1], Numerator[#1]} &)[
%t A195577 p[{r, z}]] (* A195577, A195578 *)
%t A195577 Sqrt[a^2 + b^2] (* A195579 *)
%t A195577 (* _Peter J. C. Moses_, Sep 02 2011 *)
%Y A195577 Cf. A195500, A195578, A195579.
%K A195577 nonn,frac
%O A195577 1,2
%A A195577 _Clark Kimberling_, Sep 21 2011
%E A195577 Typos in crossrefs fixed by _Colin Barker_, Jun 04 2015