f(1) = 1/4
f(1) = 4f(1)f(0)+f(1)
f(0) = 0
f(2) = 4f(1)f(1)+f(0)=1/4
f(3) = 4f(2)f(1)+f(2) = 1/4 + 1/4 = 1/2
f(4) = 4f(2)f(2)+f(0) = 1/4
..
f(2011) = 1/2
f(1) = 1/4
f(1) = 4f(1)f(0)+f(1)
f(0) = 0
f(2) = 4f(1)f(1)+f(0)=1/4
f(3) = 4f(2)f(1)+f(2) = 1/4 + 1/4 = 1/2
f(4) = 4f(2)f(2)+f(0) = 1/4
..
f(2011) = 1/2