Setting up a while loop

For an introduction to MATLAB, Ive been working on the following problem, however i keep getting the anwser for a_n and b_n as 0

my code is as follows;

n = 0

fprintf('a_n  |  b_n\n')

a_n = (6/sqrt(3))*((-1)^n/(3^n(2*n+1)));

b_n = 16*((-1)^n/5^(2*n+1)*(2*n+1))-4*((-1)^n/239^(2^n+1)*(2*n+1));

a_n_Error = abs(a_n - pi);

b_n_Error = abs(b_n - pi);

tol = 1e-6;

while a_n_Error >= tol && b_n_Error >= tol

      n = n+1;

      a_n = (6/sqrt(3))*((-1^n)/(3^n)*(2*n+1));

      b_n = 16*((-1^n)/(5^(2*n+1))*(2*n+1)) - 4*((-1^n)/(239^(2^n+1))*(2*n+1));

      a_n_Error = abs(a_n - pi);

      b_n_Error = abs(b_n - pi);

      fprintf('%10.6f  |  %10.6f\n', a_n, b_n)

end

[Geoff Hayes]

Zain - the equations in the attached pdf indicate that you should be adding/summing the a_n from the current iteration with the a_n from the previous iteration

 a_n = a_n + (6/sqrt(3))*((-1^n)/(3^n)*(2*n+1));

Same for b_n. You will also need to be careful with the order of operations and your placement of the brackets. Please confirm if the above is actually is how described in the pdf.