Frog on the Lily Pads

Level 5●●●●○ Hard~7 min

Problem

A frog starts on pad

1

of pads numbered

1,2,\dots,N

in a line. From pad

i

it jumps to a pad chosen uniformly at random among the strictly higher pads

\{i+1,\dots,N\}

. What is the expected number of jumps to reach pad

N

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