Question

怎么用mathematica求通项

Answer 1

In[1]:= res = RSolve[{a[n + 3] == p*a[n] + q*a[n + 2]}, a[n], n]

Out[1]= {{a[n] ->

C[1] Root[-p - q #1^2 + #1^3 &, 1]^n +

C[2] Root[-p - q #1^2 + #1^3 &, 2]^n +

C[3] Root[-p - q #1^2 + #1^3 &, 3]^n}}

这个带任意常数.

有p,q实际数值,前三项值就可算具体了