Data update

Task/Arithmetic-derivative/C-sharp/arithmetic-derivative.cs

@@ -0,0 +1,30 @@
+using System.Numerics;
+
+static BigInteger Derivative(BigInteger k)
+{
+    if (k < 0) return -Derivative(-k);
+    if (k < 2) return 0;
+    if (k.IsEven) return 2 * Derivative(k / 2) + k / 2;
+    BigInteger m = 3;
+
+    while (m * m <= k && (k % m) != 0)
+        m += 2;
+
+    var n = k / m;
+    if (m * n != k || m == 1 || n == 1) return 1;
+    return n * Derivative(m) + m * Derivative(n);
+}
+
+for (var i = -99; i <= 100; i++)
+{
+    Console.Write($"{Derivative(i),6}");
+    if (i % 10 == 0) Console.WriteLine();
+}
+
+BigInteger p = 1;
+
+for (var n = 1; n <= 20; n++)
+{
+    p *= 10;
+    Console.WriteLine($"⅐ D(10^{n}) = {Derivative(p) / 7}");
+}