(1n+1)+(1n+2)=(189x+13)(n+2+n+1(n+1)(n+2))=(189n+13)(2n+3)(9n+13)=18(n+1)(n+2)18n2+26n+27n+39=18(n2+3n+2)18n2+53n+39=18n2+54n+3639−36=n∴n=3