48, 23,?, 4.25, 1.125?

Series pattern
(2 x Previous element) - 1
? Missing term = (2 x 65) - 1 = 130 - 1 = 129

Series pattern
+3, +6, +9, +12, +15, +18
? Missing term = 57 + 18 = 75

Series pattern
1², 3², 5², 7², 9², 11²
? Missing term = 1² = 1

Series pattern
Every next element = 3 x previous element
? Missing term = 3 x 36 = 108

A = (a + b)/2,
1/H = (1/a + 1/b)/2
? H = 2ab/(a +b),
G = ?ab
? A x H = {(a + b)/2} x {2ab/(a + b)} = ab = G²
? A x H = G²

Series pattern = (5 x Previous element) + 5
? Missing term = (5 x 130) + 5 = 655

Series pattern
1², 3², 5², 7², 9², 11²
So missing term = 11² = 121

Series pattern
+ 13, + 26, + 39, + 52, + 65
? Missing term = 132 + 65 = 197

Series pattern
Previous number/5
? Missing term = 244/5 = 48.8

Series pattern
12 x 1 + 3 x 1 = 15
15 x 2 + 3 x 2 = 36
36 x 3 + 3 x 3 = 117
Should come in place of ?
117 x 4 + 3 x 4 = 480
480 x 5 + 3 x 5 = 2415
2415 x 6 + 3 x 6 =14508