SQL Server help tables?
spt_values is not exactly a help table for your use. It is an undocumented system table used by internal stored procedures for a variety of tasks.

Since it contains neither unique nor contiguous numbers, and because it is undocumented and unsupported (and could simply vanish in a future version), I strongly recommend you don't use this table for anything.

You can always generate a sequence based on row_number from documented and supported system views, such as sys.all_objects, sys.all_columns, or a cross join of the two if you need a large number.

Or just build a Numbers table and store the numbers for yourself. This is likely to be more efficient in most cases because, if you use it enough, it will always be accessed in memory without having to calculate the sequence.