Looping should be fairly efficient way of doing that and if you have to do it often you could convert it into a function. Below is very simple version of the function
Names Default To Here(1);
idx_char = function({letter, start = 1, end = 8}, {Default Local},
letter_list = {};
For(i = start, i <= end, i++,
Insert Into(letter_list, letter || char(i))
);
return(letter_list);
);
idx_char("Y", 1, 5); //{"Y1", "Y2", "Y3", "Y4", "Y5"}
-Jarmo