Combinatorics · Permutations · Records and minima · Counting by positions
An entry of a permutation is called right-minimal if it is smaller than every entry standing to its right. For example, in the permutation
the right-minimal entries are the ones in the second and in the fifth place, namely \(1\) and \(3\).
How many permutations of the set \(\{1, 2, \ldots, 8\}\) have a right-minimal entry in the second place and a right-minimal entry in the fifth place (and possibly in further places as well)?
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Serbian Regional Competition 2007, high school grade I, category A, problem 3. Organized by the Mathematical Society of Serbia (DMS). Source