Here are three more pictures generated with Jim's formula published in his FOTD for April 10 2013:

http://bprentice.webenet.net/Fractal%20Images/Set%2018/BP_18_12a.png

http://bprentice.webenet.net/Fractal%20Images/Set%2018/BP_18_12b.png

http://bprentice.webenet.net/Fractal%20Images/Set%2018/BP_18_12c.png

Brian Prentice