10.
定义:\(a\)是不为\(1\)的有理数,我们把\(\dfrac{1}{1-a}\)称为\(a\)的差倒数,如:\(2\)的差倒数是\(\dfrac{1}{1-2}=-1\),\(-1\)的差倒数是\(\dfrac{1}{1-(-1)}=\dfrac{1}{2}.\)已知\({{a}_{1}}=-\dfrac{1}{3}\),\(a_{2}\)是\(a_{1}\)的差倒数,\(a_{3}\)是\(a_{2}\)的差倒数,\(a_{4}\)是\(a_{3}\)的差倒数,\(……\),依此类推,则\(a_{2018}=\)________.