An Extension of the Euler Phi-function to Sets of Integers Relatively Prime to 30

Mbakiso Fix Mothebe, Ben T. Modise
2016 Journal of Mathematics Research  
Let $n \geq 1$ be an integer and let $S= \{1,7,11,13,17,19,23,29\},$ the set of integers which are both less than and relatively prime to $30.$ Define $\phi_3(n)$ to be the number of integers $x, \; 0 \leq x \leq n-1,$ for which $\gcd(30n, 30x+i) = 1$ for all $i \in S.$ In this note we show that $\phi_3$ is multiplicative, that is, if $\gcd(m, n)=1,$ then $\phi_3(mn)=\phi_3(m)\phi_3(n).$ We make a conjecture about primes generated by S.
doi:10.5539/jmr.v8n2p45 fatcat:klg47v26vredzdrtrmmdot6aba