demonstrations.wolfram.com The Wolfram Demonstrations Project contains thousands of free interactive visualizations, with new entries added daily. The Euler phi (?) function (also called the totient function) is important in number theory; ?(n) is the number of positive integers less than or equal to n that have no factor in common with n. For example, TagBox[RowBox[{RowBox[{?, (, 5, )}], =, 4}], … Contributed by: Robert Baillie
0 Comments.