MathDB
Two sets

Source: 2010 AIMEII #8

April 1, 2010
AIME

Problem Statement

Let N N be the number of ordered pairs of nonempty sets A \mathcal{A} and B \mathcal{B} that have the following properties: • \mathcal{A} \cup \mathcal{B} \equal{} \{1,2,3,4,5,6,7,8,9,10,11,12\}, • \mathcal{A} \cap \mathcal{B} \equal{} \emptyset, • The number of elements of A \mathcal{A} is not an element of A \mathcal{A}, • The number of elements of B \mathcal{B} is not an element of B \mathcal{B}. Find N N.