Solution: This is equivalent to finding the number of ways to partition 6 distinct elements into 2 non-empty subsets, which is the Stirling number of the second kind $S(6, 2)$. The formula for $S(n, 2)$ is $2^{n-1} - 1$. For $n = 6$:

Wed, 06 May 2026 01:36:41 +0000

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