n=(1+2⁰+2¹+2²+2³+2⁴....+2²⁰¹⁸= ( 2²⁰¹⁹ - 1)-1= 2²⁰¹⁹ - 2
U (2²⁰¹⁹)= U(2²⁰¹⁶ *2³)= U (2⁴)⁵⁰⁴ * U(8)=U(16)*U(8)=U(6*8)=U(48=U(8)
U(8)-U(2)=U(6)= 6
In cazul in care ex este scris gresit cu un 1 in plus in sirul de mai sus:
Vei avea : S=2²⁰¹⁹ - 1
U(8)*U(1)= U(8)=8