I want to define a function like this:

```
n_H = 0.9 # constant .
x = np.array([16.7, 16.5, 16.1, 15, 13.5,14.2, 14.9, 13.7])# example to test
D = np.array([0, 1, 4, 7, 16, 31, 64, 127])
Sec_nucli = []
x = []
D = []
Sec_nucli[i]= n_H *D[i]* x[i]
```

where x, D are variables come from another functions, I put it as an array(just as a test here!!).

What I want is to make a for loop for the function Sec_nucli, that every time I use deferent value for x,D, and Sec_nucli. For that reson I put [i], infront of these variable(I dont know how can I write it)?!!. Could you please help me to write the function correctly?

Thank you for your help.