1, 6, 8, 3, 7, ...

Crypto hint: REBMU NTIGI DEERH TASTI

I'm not sure if Federico's assessment of requiring the next numebr in the sequence be the "next lowest unused number" is correct, but assuming it is, I wondered what words could be encoded using this method.

I think the only letters which are allowable in the English language are:  e, o, r, x, n, t, y, and d (you can add 'L' to the list if you're willing to type out 100 zeroes every time you want to use 'googol').  Since the number of integers in infinite, I don't think there is any limit to the number of times each letter can appear (you're limited to one 'L' if you're not allowed to reuse the same number).

Perhaps Charlie has a program that can list every word that contains only those letters.