Next in my collection of simple basic formulas: ZC Circle. This formula like others also can be parametrized with a parameter delta:

Delta Start Value ZC Circle Remark
1.0 4.0
2.0 2.598076 symmetry is starting to show
3.0 2.116535 threefold symmetry
4.0 1.869186 symmetry goes on
5.0 1.717163 fivefold
9.0 1.435055 9 small heads
20.0 1.222645 20 small heads now