# Special rhombii

There are two parts to this puzzle, but I am posting the other part tagged with ‘mathematics’ because it isn’t really a number sequence problem. Part I Find the next number in the sequence: 1,2,3,7,16,65,?

It's a bit like the Fibonacci series, but instead of $$a(n) = a(n-1) + a(n-2)$$, it's $$a(n) = a(n-1) + a(n-2)^2$$