Permutation questions- urgent help needed

pckeller
Thu, 24 Jan 2013 11:45:10 +0000

@Dr Steve

Your example is more than helpful – it is critical! Without it, I would not have known that we were to count 1+2 and 2+1 as distinct. It’s still a hard problem, but now maybe I’m on to it :)

Also, no one has posted an answer to my earlier counting problem:

How many two-letter codes can be made using only the first 8 letters of the alphabet if letters cannot be repeated and vowels cannot follow consonants?

I do think that question falls within SAT difficulty…

I’ll IM you if I figure out your puzzle before the usual CC top guns post the answer.