Sam and Pete, two perfectly intelligent logicians, are sitting facing each other, each with a hat on. The number on Pete's hat, they are told, is the sum of two integers larger than 1; the number on Sam's hat is the product of these two integers. The following conversation ensues:

Sam: I don't know the number on my hat.
Pete: I don't know the number on my hat.
Sam: I don't know the number on my hat.
Pete: I don't know the number on my hat.
Sam: I don't know the number on my hat.
Pete: I don't know the number on my hat.
Sam: OK, now I know the number on my hat.
Pete: And I know the number on mine.

What are the numbers on Pete's and Sam's hats?