Does anyone know of a free graph plotting app for windows (or online) that can plot something like this?
X_{n+1}= r sin (π * X_{n})

I'd like to suggest WolframAlpha, but it has got troubles with the "r*", the best I could do is this. Hope it helps. 


I'd try Gnuplot or Octave/Matlab. If you had an Apple, the builtin Grapher would do the job. Also, Spacetime (Win+Mac) looks promising. 


See Science: Math: Software: Graphing for a few dozens of plotting applications. 


I would recommend matplotlib (requires some basic python knowledge). The documentation is still under development, so mastering MPL can take some time, but it's obviously worth it in the end, if you take a look at the examples here. 

