WolframAlpha, 369368 bytes

General format:

u+<character code in hexadecimal>

Exceptions:

Character   Code
+           chr43plus
0           1-1
1           0!
2           1+1
3           1+2
4           2+2
5           2+3
6           3!
7           3+4
8           4+4
9           4+5
u           U+75

Here is the full list:

u+20
u+21
u+22
u+23
u+24
u+25
u+26
u+27
u+28
u+29
u+2A
chr43plus
u+2C
u+2D
u+2E
u+2F
1-1
0!
1+1
1+2
2+2
2+3
3!
3+4
4+4
4+5
u+3A
u+3B
u+3C
u+3D
u+3E
u+3F
u+40
u+41
u+42
u+43
u+44
u+45
u+46
u+47
u+48
u+49
u+4A
u+4B
u+4C
u+4D
u+4E
u+4F
u+50
u+51
u+52
u+53
u+54
u+55
u+56
u+57
u+58
u+59
u+5A
u+5B
u+5C
u+5D
u+5E
u+5F
u+60
u+61
u+62
u+63
u+64
u+65
u+66
u+67
u+68
u+69
u+6A
u+6B
u+6C
u+6D
u+6E
u+6F
u+70
u+71
u+72
u+73
u+74
U+75
u+76
u+77
u+78
u+79
u+7A
u+7B
u+7C
u+7D
u+7E