Add to a array using a formula based on the last entry in an array n number of times

I’m attempting to build an array from a known starting value that appends to itself based on a formula that includes the last number of the list. I’d like to do this a specified number of times. So for example:

List starts at 5
The formula I use = last number in a list X 2
The new entry to the list is 10
The next new entry is 20

My non-working code is below:

mean = 198
standard_deviation = 85

list = [((mean)-(standard_deviation*3))]
list.append(((list[-1])+(standard_deviation*.1)))
print(list)

[-55.930192782739596, -47.4592697321513]

I’d like to be able to tell the array to stop after 30 entries.

Answer

list = [((mean)-(std*3))] 
for n in range(60):      
    list.append(((list[-1])+(std*.1)))