The next logical letter would be w.
This pattern starts at the first letter, then the last letter, then the second letter, then the second to last, the third, third to last, and so on.
W(2) = 2^2 + 2 = 4 + 2 = 6
u(w(2)) = -x -2 = -6 - 2 = -8
answer: u(w(2)) = -8
1 + 2^1 = 3
3 + 2^2 = 7
7 + 2^3 = 15
15 + 2^4 = 31
31 + 2^5 = 63
63 + 2^6 = 127
so the next two terms in the sequence 1, 3, 7, 15, 31, is 63 and 127.
The percent is 167% have a good day