The maximum number of nodes on level i of a binary tree is 2^(i-1). This is because each level in a binary tree doubles the number of nodes from the previous level. For example, the root of a binary tree is at level 1 and has 1 node, the next level (level 2) has 2 nodes (left and right children of the root), the next level (level 3) has 4 nodes (left and right children of the left and right children of the root), and so on.