Data commit

Task/Tau-number/Java/tau-number.java

@@ -0,0 +1,37 @@
+public class Tau {
+    private static long divisorCount(long n) {
+        long total = 1;
+        // Deal with powers of 2 first
+        for (; (n & 1) == 0; n >>= 1) {
+            ++total;
+        }
+        // Odd prime factors up to the square root
+        for (long p = 3; p * p <= n; p += 2) {
+            long 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;
+    }
+
+    public static void main(String[] args) {
+        final long limit = 100;
+        System.out.printf("The first %d tau numbers are:%n", limit);
+        long count = 0;
+        for (long n = 1; count < limit; ++n) {
+            if (n % divisorCount(n) == 0) {
+                System.out.printf("%6d", n);
+                ++count;
+                if (count % 10 == 0) {
+                    System.out.println();
+                }
+            }
+        }
+    }
+}