I would recommend something like this, where you have RAS followed by a randomized 6 digit alphanumeric code so it will be unique and wont run out of options for a very long time
Concatenate("RAS",Concat(
ForAll(
Sequence(6),
First(
Sort(
Table(
{Var:"1", Val:Rand()}, {Var:"2", Val:Rand()}, {Var:"3", Val:Rand()},
{Var:"4", Val:Rand()}, {Var:"5", Val:Rand()}, {Var:"6", Val:Rand()},
{Var:"7", Val:Rand()}, {Var:"8", Val:Rand()}, {Var:"9", Val:Rand()},
{Var:"0", Val:Rand()}, {Var:"A", Val:Rand()}, {Var:"B", Val:Rand()},
{Var:"C", Val:Rand()}, {Var:"D", Val:Rand()}, {Var:"E", Val:Rand()},
{Var:"F", Val:Rand()}, {Var:"G", Val:Rand()}, {Var:"H", Val:Rand()},
{Var:"I", Val:Rand()}, {Var:"J", Val:Rand()}, {Var:"K", Val:Rand()},
{Var:"L", Val:Rand()}, {Var:"M", Val:Rand()}, {Var:"N", Val:Rand()},
{Var:"O", Val:Rand()}, {Var:"P", Val:Rand()}, {Var:"Q", Val:Rand()},
{Var:"R", Val:Rand()}, {Var:"S", Val:Rand()}, {Var:"T", Val:Rand()},
{Var:"U", Val:Rand()}, {Var:"V", Val:Rand()}, {Var:"W", Val:Rand()},
{Var:"X", Val:Rand()}, {Var:"Y", Val:Rand()}, {Var:"Z", Val:Rand()}
),
Val,SortOrder.Ascending)
).Var
),
Value
))
