Consider the curve y=tan−1x and a point A(1,4π) on it. If the variable point Pi(xi,yi) moves on the curve for i=1,2,3,…,n ( n∈N ) such that yr=∑m=1rtan−1(2m21) and B(x,y) be the limiting position of variable point Pn as n→∞ , then the value of reciprocal of the slope of AB will be