Im trying to understand the following. We have l_1(R)=( x=x_n in l(R): summation from n=1 to infinity for absolute value of x_n). It says that this summation converges, but converges to what? Also , its says (1) is not in l_1(R) but 1/n^2 is. Can some one explain how these are so. This is not homework, just trying 2 gain an understanding. Thanks.