How to change the number of rows selected according to a value in another cell

Hi there

I was wondering if you could change the amount of rows selected (ie. sum(H1:H30)) to be a function of another cell without using an if statement.

ie cell value =30
sum(H1:H30)

cell value = 60
sum(H1:H60)

Cell value = 90
sum(H1:H90)