symsum indexing with matrix

i want to sum this:

The code i used:

syms j

S=[0,1,0,0,0;1/2,0,1/2,0,0;0,1/2,0,1/2,0;0,0,1/2,0,1/2;0,0,0,1,0];

C1=symsum(S(1,j),j,1,5);

The code reterned me error. I want to do the polynomial summation as shwon above. l also would like to extract the element in matrix S for different j. Could you tell me what is the correct code i need to use? Thank you.