1!×3-2!×4+3!×5-4!×6+……+2015!×2017-2016!=1!×2+1!-2!×3-2!+3!×4+3!-4!×5-4!+……+2015!×2016+2015!-2016!=2!+1!-3!-2!+4!+3!-5!-4!+……+2016!+2015!-2016!=1!=1