clc
clear all
close all

x = 4.2
n = 5;
pseries= zeros(N, 1);
pseries(1) = 2*x^2 / 6;

for i = 2:N
    pseries(i) = pseries(i-1) + pseries(i-1) * (-8 * x^2) / ((2*i) *(2*i + 1));
end

pseries