## Infinite Arbitrary Base Conversion Calculator

Examples:

- 01234567890abcdef
- 0123456789abcdefghijklmnopqrstuvwxyz
- 00123456789abcdefghijklmnopqrstuvwxyz (An extra 0 to keep the leading 0 but the mapping is no longer one-to-one!)
- 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
- 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_
- 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_

This is a form to convert numbers in arbitrary bases with no limits in integers. The computation is done on the server side.
It uses the algorithm described in here except `rindex`

is used instead for duplicate letters such as extra 0.
Inspired by this JavaScript implementation.