A组
1.(1)n(n+1) (2)n^2 (3)98550 (4)494550
2.(1)d=17/13,n=27 (2)a1=11,an=23 (3)n=15,an=-3/2 (4)a1=-38,Sn=-360
3.45500m
4.n=4
5.665
6.1472
过程太多了,难得打
A组
1.(1)n(n+1) (2)n^2 (3)98550 (4)494550
2.(1)d=17/13,n=27 (2)a1=11,an=23 (3)n=15,an=-3/2 (4)a1=-38,Sn=-360
3.45500m
4.n=4
5.665
6.1472
过程太多了,难得打