Well I'm no python expert but I presume you've hit the stack limit. That's the problem with recursion, it's great when you don't have to recurse very many times but no good when the number of recursions gets even moderately big.
The ideal alternative is to rewrite your algorithm to use iteration instead.
Edit: Actually having looked closer your specific error you can get past it by changing sys.getrecursionlimit. That'll only take you so far though. Eventually you'll get a stackoverflow exception which brings me back to my original point.
