a(n) = 2*a(n-1)^2 - 2*a(n-2)^2 with a(0) = 0, a(1) = 1.

A061999

a(n) = 2*a(n-1)^2 - 2*a(n-2)^2 with a(0) = 0, a(1) = 1.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =6a(4) =64a(5) =8120a(6) =131860608

External references