3610: Little Elephant and LCM
Description
The Little Elephant loves the LCM (least common multiple) operation of a non-empty set of positive integers. The result of the LCM operation of k positive integers x1,x2,...,xk is the minimum positive integer that is divisible by each of numbers xi.
Let's assume that there is a sequence of integers b1,b2,...,bn. Let's denote their LCMs as lcm(b1,b2,...,bn) and the maximum of them as max(b1,b2,...,bn). The Little Elephant considers a sequence b good, if lcm(b1,b2,...,bn)=max(b1,b2,...,bn).
The Little Elephant has a sequence of integers a1,a2,...,an. Help him find the number of good sequences of integers b1,b2,...,bn, such that for all i (1≤i≤n) the following condition fulfills: 1≤bi≤ai. As the answer can be rather large, print the remainder from dividing it by 1000000007 (109+7).
The first line contains a single positive integer n (1≤n≤105) − the number of integers in the sequence a. The second line contains n space-separated integers a1,a2,...,an (1≤ai≤105) − sequence a.
In the single line print a single integer − the answer to the problem modulo 1000000007 (109+7).
4
1 4 3 2
15
2
6 3
13