alphalph – Convert numbers to letters

Provides commands \alphalph and \AlphAlph. They are like \number but the expansion consists of lowercase and uppercase letters respectively (1 to a, 26 to z, 27 to aa, 52 to zz, 53 to ba, 702 to zz, 703 to aaa, etc.). Can be used as a replacement for LaTeX's \@alph and \@Alph macros.

The package is part of the oberdiek bundle.