a) 20, 22, 24, 26, 28, 30, 32 . . . (20+2=22, 22+2=24, 24+2=26 . . .)
b) 2, 4 , 8, 16, 32, 64, 128 . . . (2*2=4, 4*2=8, 8*2=16, 16*2=32...)
c) 1, 3, 9, 27, 81, 243 . . . (1*3=3, 3*3=9, 9*3=27, 27*3=81, . . .)
g) 1, 4, 9, 16, 25, 36, 49 . . . (1+3=4, 4+5=9, 9+7=16, 16+9=25, 25+11=36, ...)
d) 2, 5, 4, 8, 6, 11, 8, 14, 10, 17, 12, . . . (2+3=5, 5-1=4, 4+4=8, 8-2=6, 6+5=11, 11-3=8, 8+6=14, 14-4=10, . . .)
e) 1, 8, 27, 64, 125, 216, ... (1³=1, 2³=8, 3³=27, 4³=64, 5³=125, ...)