a(n) = 2*a(n-1)^2 - 1, if n>1. a(0)=1, a(1)=3.

A001601

a(n) = 2*a(n-1)^2 - 1, if n>1. a(0)=1, a(1)=3.

Terms

    a(0) =1a(1) =3a(2) =17a(3) =577a(4) =665857a(5) =886731088897

External references