n=98, S(1..n) = n*(n+1)/2, S(2..n) = n*(n+1)/2 - 1
S = n*(n+1)/2 - 1 = 98*99/2 - 1 = 49*99 - 1 = 4851 - 1 = 4850
n=98, S(1..n) = n*(n+1)/2, S(2..n) = n*(n+1)/2 - 1
S = n*(n+1)/2 - 1 = 98*99/2 - 1 = 49*99 - 1 = 4851 - 1 = 4850