36 lines
942 B
C++
36 lines
942 B
C++
#include <iomanip>
|
|
#include <iostream>
|
|
|
|
// See https://en.wikipedia.org/wiki/Divisor_function
|
|
unsigned int divisor_count(unsigned int n) {
|
|
unsigned int total = 1;
|
|
// Deal with powers of 2 first
|
|
for (; (n & 1) == 0; n >>= 1)
|
|
++total;
|
|
// Odd prime factors up to the square root
|
|
for (unsigned int p = 3; p * p <= n; p += 2) {
|
|
unsigned int count = 1;
|
|
for (; n % p == 0; n /= p)
|
|
++count;
|
|
total *= count;
|
|
}
|
|
// If n > 1 then it's prime
|
|
if (n > 1)
|
|
total *= 2;
|
|
return total;
|
|
}
|
|
|
|
int main() {
|
|
const unsigned int limit = 100;
|
|
std::cout << "The first " << limit << " tau numbers are:\n";
|
|
unsigned int count = 0;
|
|
for (unsigned int n = 1; count < limit; ++n) {
|
|
if (n % divisor_count(n) == 0) {
|
|
std::cout << std::setw(6) << n;
|
|
++count;
|
|
if (count % 10 == 0)
|
|
std::cout << '\n';
|
|
}
|
|
}
|
|
}
|