Print a letter Fibonacci Given N (2 &lt;= N), print N lines of the letter Fibonacci series like this (i.e. N = 5)
First, start with a and b:

a
b


Next, add the two lines.

a
b
ab


Keep adding the last two lines.

a
b
ab
bab


Keep going...

a
b
ab
bab
abbab


And we're done.

Remmeber, this is code-golf, so the code with the fewest bytes wins.
Python 2, 41 bytes

Saved 3 bytes thanks to @xnor

a,b="ab";exec"print a;a,b=b,a+b;"*input()


Test on Ideone

Simply follows the recursive definition.