# Can calc auto-increment letters?

In Calc, if you fill in adjacent cells with incremented numbers, then select both cells and drag, Calc will auto-populate with the series, as in columns C and D here:

I have tried doing this with letters -- "a", "b", > select, drag ... -- but it just repeats "a b a b a b" instead of incrementing the series.

So, can Calc do with letters what it does with numbers?