Well-hidden in the documentation is the following:
" Form of Indexing. Within the list of indices for a sliced variable, one of these indices is of the form i, i+k, i-k, k+i, or k-i, where i is the loop variable and k is a constant or a simple (nonindexed) broadcast variable; and every other index is a scalar constant, a simple broadcast variable, colon, or end. "
Since C(i,2:4) contains non-scalar indices 2:4, your code violates the above. But anyway, if there is a fixed subarray that you want to slice, it makes more sense to pre-extract that sub-array and send that to parfor instead, as below. That way, you reduce data traffic to the parallel workers.
C=array2table(NaN(n,5)); % Error with line 15
Csub=C(:,2:4);
parfor i=1:n,
A = zeros(1,n);
for j=1:n,
A(1,j)=i+j-1;
end
B=array2table(A);
Csub(i,:)=B(1,[2,4,5]);
end
C(:,2:4)=Csub;
