We can write,

Thus, the exponent is chaning from to .

In sigma notation,

Because everything else remains fixed.

The sum of this series is geometric.

Use the geometric series formula with constant ratio .

You can write,1+1/2+1/3+...+1/100

Only the denominator is changing from to .

In sigma notation,

There is no nice formula for this series, but we can approximate it with the natural logarithm.

Approximately the value is .