How to use Matlab symsum?

Question

This is the question of a heat transform problem. Basically, I want to solve the value when (x,t) = (0.3,0.01)

This is the code I wrote:

answer=T(0.3,0.01);

disp(answer);

function y=T(x,t)

syms n

f=(sin(1/2*n*pi))*sin(n*pi*x)*(exp(-(n^2*pi^2*t)/n^2));

sig=symsum(f,n,1,inf);

y=8/pi^2*sig;

end

However, the result is NAN!

I found out that the problem was in "symsum".

Could you please try to help me fix this problem, thank you!