Question: how to build double subscript name on the fly? "v__i" where "i" is variable?

I needed to make symbolic vector, as in  


The problem is that, the proc called, has to create this vector on the fly, since the dimension changes on each call. So I used seq command to generate it. But seq did not work. I tried



After looking more at it, It seems to have nothing to do with evaluation. If the subscript index is variable, it does not work.


  return (v__i);
end proc;


One way is to use v[i] instead of v__i, and now it works:


But since subscripted variable are supposed to be safer than indexed variable, I wanted to use v__i and not v[i].


Why it does not work? And is there a workaround this?  

ps. I could always do this 


But this seems like a hack to me and I do not know why it should be needed.

ps. any one knows where help on "__" is in Maple? I can't find it. doing ?__ turns out nothing. I do not know under what name help on double subscript is in maple.

Maple 2020.1

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