WolframAlpha computational knowledge AI
(3+(-1)^n)/(5+3(-1)^n)2^((2n-5+(-1)^n)/4)+1/(5+3(-1)^n)6^((2n-1+(-1)^n)/4)+(81-27(-1)^n)/(5+3(-1)^n)70^((2n-5+(-1)^n)/4)-1 for n = 3