Charlie watches as a pattern develops. In month 1, he starts with 3 guppy fish in his fish tank. The next month, he finds 6 guppy fish in his tank. The following month, he finds 11 guppy fish in his fish tank. Write an expression to model the pattern of guppy fish in Charlie’s fish tank. Use your expression to determine the number of guppy fish Charlie will observe in month 6.

In month 6, Charlie should observe
_______
guppy fish.