1. 1+3+5+...+(2n-1)=2^n THIS FORMULA IS WRONG 2. 7^(2n+1) is divided by 8 THIS STATEMENT IS WRONG 3. 3^(4n+2) + 2.4^(3n+1) is exactly divisible by 7 THIS STATEMENT IS WRONG (I checked it at n = 1, 2, 3, 4, 5) 4. n^(4) + 4n^(2) + 11 is a multiple of 16 for all odd positive integer n.