Write an python function that gets n and returns the nth value in the Pell sequence. Pell sequence is defined by
P(n) = 2*P(n-1) + P(n-2) while P(0) = 0 and P(1) = 1. Use your code to generate and provide the first 10 values of Pell sequence.

def pell(n):

 

Run an analysis of the function developed in above and find its T(n) and big O performance.  Is finding the nth element of Pell sequence faster than bubble sort? Is it faster than finding the nth element of the Fibonacci series?