Counting & ProbabilitySuperchallengeRecursion, Catalan Numbers & Generating Functions
Recursion, Catalan Numbers & Generating Functions · Superchallenge problem
A mountain range is drawn with upstrokes and downstrokes: a path of unit diagonal steps that starts on the ground, ends on the ground, and never goes below it. A foothill is an upstroke from the ground immediately followed by a downstroke back to the ground. How many mountain ranges have no foothill?