
Related Articles
- For each such pair (m, k), we count the number of ways:
- Choose 2 distinct positions for R’s: both < m? No: R’s must be all \( < k \), and max \( R \leq m \), and \( m < k \), so all R positions ∈ [1, m-1]? No: if \( k \geq m+1 \), we need R’s all < k, but \( m < k \), so R’s can be in [1, k−1], but they must all be < k and their max < k, but we require max R < k — always true if R’s are in [1, k−1]. But we need **both R’s < k**, which is automatic if we choose from 1 to k−1, but the condition is only upper bound on L’s.
- Wait — correction: we need **all R’s before all L’s**, i.e., every R position < every L position.
- Let \( m = \max(\text{R positions}) \), \( n = \min(\text{L positions}) \), require \( m < n \)
- Now, \( m \geq 2 \), \( n \leq 5 - m \), but \( n > m \), and \( n \geq m+1 \)
- So for each \( m = 2,3,4 \), and \( n = m+1, m+2, \dots, 5 \), we count: