1000-100%
5-х
х=5*100/1000=0.5%
aₙ₊₁ = 2aₙ - 1
a₁=3
a₂ = 2*3 - 1 = 5
a₃ = 2*5 - 1 = 9
a₄ = 2*9 - 1 = 17