As can be seen from the above formula, the expansion coefficient of (1+x) 2n is C2n/k * 1 (2n-k), that is, C2n/k, that is, binomial coefficient.

Because the power of (1+x) is 2n(n∈N*) is even, it is concluded that C2n/n is the maximum binomial coefficient value (that is, the maximum coefficient value), and the term corresponding to the coefficient C2n/n is n+ 1 term.

To sum up, the answer is n+ 1