Initial data commit

Task/Totient-function/Go/totient-function-2.go

@@ -0,0 +1,46 @@
+package main
+
+import "fmt"
+
+func totient(n int) int {
+    tot := n
+    for i := 2; i*i <= n; i += 2 {
+        if n%i == 0 {
+            for n%i == 0 {
+                n /= i
+            }
+            tot -= tot / i
+        }
+        if i == 2 {
+            i = 1
+        }
+    }
+    if n > 1 {
+        tot -= tot / n
+    }
+    return tot
+}
+
+func main() {
+    fmt.Println(" n  phi   prime")
+    fmt.Println("---------------")
+    count := 0
+    for n := 1; n <= 25; n++ {
+        tot := totient(n)
+        isPrime := n-1 == tot
+        if isPrime {
+            count++
+        }
+        fmt.Printf("%2d   %2d   %t\n", n, tot, isPrime)
+    }
+    fmt.Println("\nNumber of primes up to 25     =", count)
+    for n := 26; n <= 100000; n++ {
+        tot := totient(n)
+        if tot == n-1 {
+            count++
+        }
+        if n == 100 || n == 1000 || n%10000 == 0 {
+            fmt.Printf("\nNumber of primes up to %-6d = %d\n", n, count)
+        }
+    }
+}