a = 1
|  a res: 1 i: 1, last: 0, start: 1, end: 1
aa = 2
aax = 4
|  x res: 4 i: 3, last: 2, start: 4, end: 1
aaxx = 8
|  x res: 8 i: 4, last: 3, start: 8, end: 1
aaxxx = 16
|  x res: 16 i: 5, last: 4, start: 16, end: 1
aaxxxx = 32
|  x res: 32 i: 6, last: 5, start: 32, end: 1
aaxxxxx = 64
|  x res: 64 i: 7, last: 6, start: 64, end: 1
aaxxxxxx = 128
|  a res: 128 i: 8, last: 1, start: 2, end: 127
aaxxxxxxa = 382
|  a res: 382 i: 9, last: 8, start: 382, end: 1
aaxxxxxxaa = 764
764