6076: Sereja和子序列

Sereja has a sequence that consists of n positive integers, a₁,a₂,...,a_n.
First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence a. Then for each sequence written on the squared paper, Sereja wrote on a piece of lines paper all sequences that do not exceed it.
A sequence of positive integers x=x₁,x₂,...,x_r doesn't exceed a sequence of positive integers y=y₁,y₂,...,y_r, if the following inequation holds: x₁≤y₁,x₂≤y₂,...,x_r≤y_r.
Now Sereja wonders, how many sequences are written on the lines piece of paper. Help Sereja, find the required quantity modulo 1000000007 (10⁹+7).

1
42

42

3
1 2 2

13

5
1 2 3 4 5

719