To answer your question: No, its not an array. I think GregSands already provided good help to this particular question:
Of course this is only useful if you work with the Formula Node, just like you did with the other solution. That being said, before you continue writing anything in LabVIEW please take your time to understand what your expressions are doing. Try to make it simpler to understand. For example, instead of trying to get this entire expression to work, start with one portion of it, like the first part:
z = 3 >> x
You have to answer the same questions as before: What do you expect this expression to return for z?
There are a lot of resources on the internet that also explain very well what these expressions do. You just need to know what to search for, so here is a translation table for you:
>> Arithmetic Shift Right
<< Arithmetic Shift Left
^ Bit Exclusive Or
& Bit And
| Bit Or
I suggest you try and understand what each of these expression does before combining them into longer expressions. Here is a full list of operations with their names for the Formula Node: http://zone.ni.com/reference/en-XX/help/371361P-01/lvhowto/precedence_of_operators_in/
I'm not an expert with Formula Nodes, but this should be possible to do without MathScript. From what I can tell the "x²" probably isn't allowed in the Formula Node, so maybe use "pow(x,2)" instead? If you get an error message please post the entire message here, maybe someone knows why this error happens.