-- Try yukicoder
-- author: Leonardone @ NEETSDKASU

main = interact $ show . solve . map read . words

mod109 = (`mod` (10^9 + 7))

solve (n:vs) = ans where
    (xs, ys) = splitAt (n+1) vs 
    zs = zip xs (reverse ys)
    ans = fst $ foldl f (0, 0) zs
    f (a, s) (x, y) = (mod109 $ a + y * (s + x), mod109 $ s + x)