Task 1: "GCD Sum

You are given a positive integer $N.
Write a script to sum GCD of all possible unique pairs between 1 and $N.

Example 1:

	Input: 3
	Output: 3

	gcd(1,2) + gcd(1,3) + gcd(2,3)

Example 2:

	Input: 4
	Output: 7

	gcd(1,2) + gcd(1,3) + gcd(1,4) + gcd(2,3) + gcd(2,4) + gcd(3,4)
"

My notes: very clearly defined.  Haven't used GCDs for a while:-)


Task 2: "Magical Matrix

Write a script to display matrix as below with numbers 1 - 9. Please make sure numbers are used once.

[ a b c ]
[ d e f ]
[ g h i ]

So that it satisfies the following:

a + b + c = 15
d + e + f = 15
g + h + i = 15
a + d + g = 15
b + e + h = 15
c + f + i = 15
a + e + i = 15
c + e + g = 15
"

My notes: clearly defined.  Constraint problem.