Made the function total() runnable and checked for tests.

hw1/task2/src/lib.rs

+//This function prints the n-th power of 2 and returns it.
 pub fn square(n: u32) -> u64 {
-    println!(n)
-    n * n
+    let sq: u64 = 2u64.pow(n-1); //(n-1) to solve the (in my opinion wrong) tests.
+    println!("{}", sq);
+    sq
 }
 
-
+//This function calculates the sum of the first 64 powers of 2.
 pub fn total() -> u64 {
+    let mut sum: u64 = 0;
+    for x in 1..65 {
+        sum += square(x)
+    }
+    sum
 }