while (n != 1)
        {
                if ( 0== (n% 2))
                        n = n/2;
                else if (0==(n%3))
                        n = n/3;
                else if (0==(n%5))
                        n = n/5;
                else if (0==(n%7))
                        n = n/7;
                else
                        n = 11*n+1;
        }

    This one cycles on e.g. 47
    47 518 259 37 408 204 102 51 17
    188 94 47

    In general let p be a prime
    if there exists a prime  q < p and q|n
        then n = n/q
    else  n = p*n +1

    Which ones have loops? All ??

        BACK