Please check the given sequence is a combination of two series.
Series 1: 19, 38, 114, …
Series 2: 2,3,4

In series 1, Pattern followed is *2, *3, so next will be *4
Next term will be 114*4 = 456

===> 19*2 = 38

===>38*3 = 114

===>114*4 = 456

The number are 1² – 1 = 0,

2² – 2 = 2,

3² – 1 = 8,  

4² – 2 = 14,

5² – 1 = 24,…….

.’. Missing number = 5² – 1 = 24.

The numbers are 11², 15², 19²,… i.e. 11², (11 + 4 * 1)², (11 + 4 * 2)²,….
.’. Missing number =(11 + 4 * 3)² =  (23)² = 529.

The pattern is + 3, + 4,….
.’. Missing number = 9 + 5 = 14.

The pattern is + 5, + 7, + 9, + 11,…
.’. Missing number = 33 + 13 = 46.

8 * 0.5 = 4
4 * 1 = 4
4 * 2 = 8
8 * 4 = 32
32 * 8 = 256

8 + 1² + 1= 10
10 + 3² + 1= 20
20 + 5² + 1= 46……..

8 * 0.5 = 4
4 * 1 = 4
4 * 1.5 = 6
6 * 2 = 12
12 * 2.5 = 30

18 * 1 + 2 = 20
20 * 2 – 4 = 36
36 * 3 + 6 = 114
114 * 4 – 8 = 448
448 * 5 + 10 = 2250

11 + 1² + 1= 13
13 + 2² + 1= 18
18 + 4² + 1= 35……..

1650/6 – 5 = 275 – 5 = 270
270/5 -4 = 54-4 = 50
50/4 -3 = 12.5 -3 = 9.5
9.5/3 -2 = 3.17-2 = 1.17
1.17/2 -1 = 0.585-1 = -0.415

520*1/5 =104
104*2/5= 41.6
41.6*3/5 = 24.96
24.96*4/5 = 19.97

11*1+(1*7) =11+7 = 18
18*2+(2*6) = 36+12 = 48
48*3+(3*5) = 144+15 = 159
159*4+(4*4) = 636+16 = 652

Clearly, the given series consists of prime numbers starting from 2. The prime number after 11 is 13.
So, 13 is the missing number.

We can observe that the above series is square of odd numbers starting from one. So our answer will be 9^2 = 81.