[henryzz]

Originally Posted by petrw1

I started this same puzzle a year ago at:
http://www.mersenneforum.org/showthread.php?t=7051

Also in 2005 by someone else at
http://www.mersenneforum.org/showthread.php?t=4756

And a related 4-9's puzzle at:
http://www.mersenneforum.org/showthread.php?t=7060

There are several links in these posts to other web sites that solve problems with 4 of just about anything and just about any set of rules you like.

thanks this is very helpful