BTW using the classroom assistant palette under Typesetting in the 5th row 4th entry you also find the standard brackets you need to do these statements. The result is this:
This looks like standard typesetting and works just fine:
v[2^-# &]
(*convergent*)
Cheers,
Marco
If you convert this to standard form it gives you yet another way of writing the same thing:
v[a_] := Piecewise[{
{"convergent", Limit[a[n + 1]/a[n], n -> \[Infinity]] < 1},
{"divergent", Limit[a[n + 1]/a[n], n -> \[Infinity]] > 1},
{"indeterminate", Limit[a[n + 1]/a[n], n -> \[Infinity]] == 1}}]
