Arithmetico-geometric Series
by James Carter
The Maths
The Sum
S = 1 + 2x + 3x^2 ..... + (n+1)x^(n-1)
xS = x + 2x^2 ....... + nx^(n-1) + (n+1)x^n
Sn = 2/(1-x) + x(1-x^(n-1))/(1-x)^2 - (n+1)x^n/(1-x)
Convergence
This converges if to Lim n^pr^n if P > 0; |r| < 1
Why won't it work properly?
