a) 5, 10, 15, 20, 25
b) 1, 3, 6, 10, 15
c) 9, 16, 25, 36, 49
d) 15, 12, 9, 6, 3, 0
e) 21, 17, 14, 10, 7, 3
f) 1, 8, 27, 64, 125, 216
g) -3, 2, -8, -3, -13, -18
h) 3/5, 5/7, 7/9, 9/11, 11/13, 13/15
i) 1, 5, 12, 22, 35, 51
j) 80, 70, 61, 53, 46, 40, 35
k) 1, 3, 7, 15, 31, 63, 127