Even term coefficient, that is, the degree of x is even.
Let x= 1, then the odd term coefficient+even term coefficient = (1+1+) 4 = 256.
Let x=- 1, then even term coefficient-odd term coefficient = (1-1+1) 4 = 0.
Up-down type
2 times the odd term coefficient =256
The sum of odd-numbered coefficients is 128.
The answer is 128.