Répondre :
n | 0 | 1 | 2 | 3 | 4
U(n) | 0.25 | 0.3125 | 0.347656 | 0.370865 | 0.387541
U(0)=1/4
U(1)=(1/4)²+1/4=5/16
U(2)=(5/16)²+1/4=89/256
U(n) | 0.25 | 0.3125 | 0.347656 | 0.370865 | 0.387541
U(0)=1/4
U(1)=(1/4)²+1/4=5/16
U(2)=(5/16)²+1/4=89/256