totientFunction: procedure options(main);
    totient: procedure(nn) returns(fixed);
        declare (nn, n, i, tot) fixed;
        n = nn;
        tot = n;
        do i=2 repeat(i+2) while(i*i <= n);
            if mod(n,i) = 0 then do;
                do while(mod(n,i) = 0);
                    n = n / i;
                end;
                tot = tot - tot / i;
            end;
            if i=2 then i=1;
        end;
        if n>1 then tot = tot - tot/n;
        return(tot);
    end totient;

    showPrimeCount: procedure(n, primeCount);
        declare (n, primeCount) fixed;
        put skip edit('There are', primeCount, ' primes up to', n) (A,F(5),A,F(6));
    end showPrimeCount;

    declare (n, primeCount, tot) fixed;
    do n = 1 to 25;
        tot = totient(n);
        put edit('phi(', n, ') = ', tot) (A,F(2),A,F(2));
        if tot = n-1 then do;
            put list('; prime');
            primeCount = primeCount + 1;
        end;
        put skip;
    end;

    call showPrimeCount(25, primeCount);
    do n = 26 to 10000;
        if totient(n) = n-1 then primeCount = primeCount + 1;
        if n=100 | n=1000 | n=10000 then
            call showPrimeCount(n, primeCount);
    end;
end totientFunction;