What was the "off-by-one" error? Using the same dictionary file, I get aeinprst = 346 which I have manually verified. This isn't brute force (as you have indicated elsewhere) - it is heuristic but appears to come up with the correct result. While I like it, I needed to know for certain which is why I wrote an exhaustive solution which amazingly finished in 12 minutes.
Well, the off-by-one error I assumed was in my code was actually in the small test dictionaries I ran, because of a spurious empty line at the end.
It is quite funny that my brute force code finds the right solution even without going through all possible combinations. I guess I was just lucky.
A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James