[o.i\#]

1)

3 7 13 21 31
5 20 51 104 185 :
3*1 + (3-1) = 5
7*2 + (7-1) = 20
13*3 + (13-1) = 51
21*4 + (21-1) = 104
31*5 + (31-1) = 185

2)

7 10 25 94 463