Hello, WWTL@WHL!

Find when: .

I see no choice but to crank out a few powers and seek a pattern . . .

. .

. .

. .

. .

. .

Ithinkwe've found the pattern . . .

We have: .

. . where: is the negative of the odd number: .

. . . . . . . is one less than

. . . . . . . is the positive value of

. . . . . . . is one more than

Therefore: .