MathCastle
Counting & ProbabilitySuperchallenge

Counting & Probability · Superchallenge problem

In how many ways can the set {1,2,3,4,5,6,7,8,9}\{1,2,3,4,5,6,7,8,9\} be partitioned into exactly four nonempty blocks (the blocks are not labeled) so that 11, 22 and 33 are in three different blocks?

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