I spent countless hours on this with a pencil and calculator in the 90's, laboriously back-fitting equations via recursion. This is the fulfilment of a dream!

I spent countless hours on this with a pencil and calculator in the 90's, laboriously back-fitting equations via recursion. This is the fulfilment of a dream! Also: 4x² + 570x + 20233 is 100% smooth (in the given range).