Question

I can generate word using 2 letters only, lets say ‘k’ and ‘e’. Length of word is from 5 – 35 characters. Each letter and len of the word are randomly chosen with rand(). Can someone tell me how much possible unique words I can produce.
Thanks.

PS are these called permutations or combinations?

Answer 1

Permutations: order matters (your case)
Combinations: order does not matter, i.e. “ke” == “ek”

N = 2^5 + 2^6 + … 2^34 + 2^35

This is a finite-length geometric series, and Wolfram Alpha tells us:
Sum[2^k, {k, 5, 35}]
68719476704
68,719,476,704 == some 69 billion