difference equation in Finnish

(mathematics) An equation involving an ordered sequence of real numbers (\left\{a_n\right\}_{n=1}^\infty) and some of its differences, where the first difference is defined as \Delta(a_n) = a_{n+1} - a_n\, and the kth difference is defined recursively as \Delta^k(a_n) = \Delta^{k-1}(a_{n+1}) - \Delta^{k-1}(a_n)\,.