f=lambda n:0**n*2or~-f(n-1)*f(n-1)+1 print(f(0))print(f(1))print(f(2))print(f(3))print(f(4))
Standard input is empty
2 3 7 43 1807
The brand new service which powers Ideone!
Widget for compiling and running the source code in a web browser!