11．在数列{an}\{a_{n}\}{an}中，a1=2a_{1}=2a1=2，a2=aa_{2}=aa2=a，且an+1=−an+3n+2(n⩾2,n∈N∗){a_{n+1}}=-{a_n}+3n+2(n\geqslant 2,n\in {N^*})an+1=−an+3n+2(n⩾2,n∈N∗)，若数列{an}\{a_{n}\}{an}单调递增，则实数aaa的取值范围为((( )))