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3.an,a1

1.:30,37,32,35,34,33,36, ,38,______2.,a4+a6=3,a5(a3+2a5+a7)=_____3. {an},a4+a6+a8+a10+a12=120, 2a10-a12 A.20 B.22 C.24 D.28319C4.{an},a1=1,3an+1-3an=1,a301= A.100 B.101 C.102 D.103B5.an}an>0,a2a4+2a3a5+a4a6=25, a3+a5 A.5 B.1 C.15 D.10A

6.{an},41,84,a17+a18+a19+a20 ( )A.7 B.8 C.9 D.10C 7.-2410,d8.{an},a1=3,an+1=an+3n(n1),