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 A195565 #9 Mar 11 2014 20:32:49
%S A195565 4,3,204,280,2280,12596,12797,831996,1149440,9341440,51622404,
%T A195565 52441603,3409523404,4710402840,38281220840,211548594996,214905676797,
%U A195565 13972226073596,19303229690880,156876433658880,866926090675204,880683411072003
%N A195565 Denominators a(n) of Pythagorean approximations b(n)/a(n) to 5/4.
%C A195565 See A195500 for a discussion and references.
%t A195565 r = 5/4; z = 26;
%t A195565 p[{f_, n_}] := (#1[[2]]/#1[[
%t A195565 1]] &)[({2 #1[[1]] #1[[2]], #1[[1]]^2 - #1[[
%t A195565 2]]^2} &)[({Numerator[#1], Denominator[#1]} &)[
%t A195565 Array[FromContinuedFraction[
%t A195565 ContinuedFraction[(#1 + Sqrt[1 + #1^2] &)[f], #1]] &, {n}]]]];
%t A195565 {a, b} = ({Denominator[#1], Numerator[#1]} &)[
%t A195565 p[{r, z}]] (* A195565, A195566 *)
%t A195565 Sqrt[a^2 + b^2] (* A195567 *)
%t A195565 (* by _Peter J. C. Moses_, Sep 02 2011 *)
%Y A195565 Cf. A195500, A195566, A195567.
%K A195565 nonn
%O A195565 1,1
%A A195565 _Clark Kimberling_, Sep 21 2011