What is the "i" of the Sedgewick's Gap Sequence formula? [closed]

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The Sedgewick's Gap Sequence can be calculated with 4*9^i-9*2^i+1 and 4^i-3*2^i+1. What is the value of "i"?

Answer 1

To perform a shellsort, you compute the gap sequence, sometimes called the increment sequence, using i starting at 1 and incrementing it until it's large enough to sensibly start sorting (Sedgewick suggests that when you get the largest gap sequence less than N/3).

Then you shellsort starting with the largest gap down to 1.

Note: the gap sequence equations you posted don't seem to agree with what's on Wikipedia's shellsort page and don't seem to work. You might want to verify the equations you want to use.