fourier series spectra plot

i am using matlab to plot fourier spectra, but i keep getting this error _Error using mupadmex Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.

If the input expression contains a symbolic variable, use the VPA function instead.

Error in sym/double (line 514) Xstr = mupadmex('symobj::double', S.s, 0);

Error in datachk (line 11) y = full(double(x));

Error in stem (line 83) h = [h specgraph.stemseries('YData',datachk(y(:,k)), xdata{:},...

Error in tes3 (line 13) stem(n,V);_

this is my code

syms n t;
T = 2*pi;
w = 2*pi/T;
n = 1:10;
a0 = 1/T*int(5*t+4*cos(3*t)+4*sin(3*t)-2*sin(2*t),t,0,T/2);
an = 2/T*int((5*t+4*cos(3*t)+4*sin(3*t)-2*sin(2*t))*cos(n*w*t),t,0,T/2);
bn = 2/T*int((5*t+4*cos(3*t)+4*sin(3*t)-2*sin(2*t))*sin(n*w*t),t,0,T/2);
sumab = 0;
for n = 1:10
    sumab = sumab + an(n)*cos(n*w*t)+bn(n)*sin(n*w*t);
end
V = a0+sumab;
stem(n,V);
what can i do to solve this problem?
thanks for your reply