This almost seems to simplistic but how about something like this.
Note that the range values and results are truncated and don't exactly match your requirements, just used the original example loop to show the general idea.

for i in range(65,70):

for j in range(65,70):

for k in range(65,70):

print chr(i),chr(j),chr(k)

...

A A A

A A B

A A C

A A D

A A E

A B A

A B B

A B C

A B D

