本帖最后由 王守恩 于 2021-9-1 12:17 编辑
"爬楼梯" LinearRecurrence[{1, 3, -3, -3, 3, 1, -1}, {0, 0, 0, 1, 0, 5, 2, 14}, n]
{0, 0, 1, 0, 5, 2, 14, 8, 30, 20, 55, 40, 91, 70, 140, 112, 204, 168, 285, 240,
385, 330, 506, 440, 650, 572, 819, 728, 1015, 910, 1240, 1120, 1496, 1360,
1785, 1632, 2109, 1938, 2470, 2280, 2870, 2660, 3311, 3080, 3795, 3542,....}
\(a(n)=\frac{2n^3-6n^2+7n-n(6n-9)\cos(n\pi)}{48}\) |