a(n) = 4^(n-1)*(2^n-1).

A016152

a(n) = 4^(n-1)*(2^n-1).

Terms

    a(0) =0a(1) =1a(2) =12a(3) =112a(4) =960a(5) =7936a(6) =64512a(7) =520192a(8) =4177920a(9) =33488896a(10) =268173312a(11) =2146435072a(12) =17175674880a(13) =137422176256

External references