This forms an arithmetic series with:
First term =8,002,000
Difference for each term= -(1/2(n^3+n^2) =31,973,323,333/7,998
Number of Terms =4,000
∑[8,002,000*n -(1/2(n^3+n^2)), n, 1, 4000]=32,005,331,333,000
Or, using AP Formula, we get:
4000/2*(8002000*2 + (31973323333/7998*3999))=32,005,331,333,000