Aflati termenul general al sirului [tex](a _{n}) _{n \geq 1}pentru care :
\frac{1}{a _{1} }+ \frac{1}{1/a2}+ \frac{1}{2/a_{3} }. . .+ \frac{1}{(n-1)/a _{n} }= \frac{n(n+1)}{2} [/tex][tex]
n \geq 1;n[/tex]∈N