Happy Number
A happy number is a number which eventually reaches 1 when the number is replaced by the sum of the square of each digit.
For example:
208 -> 2² + 0² + 8² = 68
68 -> 6² + 8² = 100
100 -> 1² + 0² + 0² = 1
Thus 208 is a happy number!
The x and y co-ordinates together represent one number.
E.g. (20,8) = 208
This is an adaptaion from the geogebra applet
https://www.geogebra.org/m/SAd8TBPQ
(by t.spillane)