MathCastle
Counting & ProbabilityHardCounting & Probability

Counting & Probability · Hard problem

A 55-character password is formed from the 2626 letters of the alphabet, with NO letter repeated, and must both start and end with a vowel (A,E,I,O,UA,E,I,O,U; since no repeats are allowed, the starting and ending vowels must be different letters). How many such passwords are possible?