That would lead to weird behavior since the OEIS is sorted by number of references, which I think prefers "interesting" solutions over straightforward ones. For (1, 2, 3), the positive integers are only ranked 5th -- the top hit are the Fibonacci numbers. It's funny to think about.
I thought about that. I thought the compiler could error with "Insufficient data for meaningful answer" until you'd added enough digits that the sequence was unambiguous.
Then I tried it in OEIS and as you say there are too many sequences that start [1,2,3,4,5,...] - I think we may be stuck with generators and yield. But they're not exactly delightful.