[cafard]

John Graham-Cumming posted something like this some years ago.

[mcconnma]

Thanks for the name, I found the article here: http://blog.jgc.org/2010/01/more-fun-with-toys-ikea-lillabo-.... However, he only solves for 16 pieces. This post and program solves for any number of pieces.

[zokier]

You an jgc also use different criteria for symmetry/rotation removal, evidenced by different count of layouts for 16 pieces (jgc 9, you 15)

[mcconnma]

I noticed that as well, I need to figure out what is the difference ...