To sort 100 items we first find an ‘hs’ such that hs ≥ 100.
For 100 items, h5 is selected. The final value (ht) is two steps
lower, or h3. Therefore sequence for the values of ‘h’ will be
13-4-1. Once the initial ‘h’ value has been determined,
subsequent values may be calculated using the formula
hs-1 = floor(hs / 3).