1.
Let [x][x] denote greatest integer less than or equal to xx. If for n∈Nn \in \mathbb{N}, (1−x+x3)n=∑j=03najxj(1 - x + x^3)^n = \sum_{j=0}^{3n} a_j x^j, then ∑j=0[3n/2]a2j+4∑j=0[(3n−1)/2]a2j+1\sum_{j=0}^{[3n/2]} a_{2j} + 4 \sum_{j=0}^{[(3n-1)/2]} a_{2j+1} is equal to