Fix the bug where the capacity is incorrectly calculated.
Fix the bug where the capacity is incorrectly calculated.

The capacity should be s timed with the number of blocks, instead of added with. Also, the block numbers are zero-based, so a "+1" is needed to get to the correct number.
Workiva/go-datastructures,Workiva/go-datastructures,tylertreat/go-datastructures,tylertreat/go-datastructures