why my Matlab code is not passing the test suite? [Cody]

https://www.mathworks.com/matlabcentral/cody/groups/3755/problems/44705

function a = ten2pow4(n)

format rat

c = zeros(1, n+1);

if n>0

c(2) = 2;

for i = 2:n

for r = 1:i-1

c(i+1) = c(i+1) + (((10^(i)/(i-1))-4^(r)*c(r+1))/(4^(i) + 1));

end

end

else

c(1) = 1;

end

c(1) = c(n+1);

a = flip(c);

end