Generate the first k terms in the sequence a(n) define recursively by
a(n+1)=p*a(n)+(1+a(n)) with p=0.9 and a(1)=0.5
Test Case
n = 2;
a = [a(1) a(2)] = [0.5000 1.9500]
The difficulty with this problem is not generating the sequence, that is trivial, but to conform to the completely arbitrary and inaccurate rounding rules of the test suite.
Something I really want to tell the one who create this problem: base on this test suite you just made, I'm positively sure that you've learned your lesson in gym class.
Check your y_correct for x=20 for extraneous whitespace characters.