Witua and Math

Witua is a little student from the University of Lviv. He enjoys studying math. Witua knows a lot of famous mathematicians like Eratosthenes, Pythagoras, Fermat, Diophantus, Furko, Gauss and so on. However, his favorite one is Euler. The only thing Witua likes more than Euler is Euler’s totient function φ. He is exploring the nature of this function. One of the steps of his work is finding φ(i)/i