I had assumed that l<5 would be understood as a constraint along the lines of <10000, and although that assumption was false, the value of the input variable never changed
...also labeling before applying it should have made it clear that that wouldn't work in that form, but I tried labeling afterwards and same thing
anyhow I then tried {}ᵐ as the entire program, with an input of [1], and it generated infinitely many [1]s for no apparent reason
I just had the strangest idea to try swapping the l and <, and it seems to actually work without the cut, because instead of constraining the length you're just constraining the number to be less than a number with that length
Until I thought of length I was using 8ḟ as an upper bound
The question body's phrasing of "incomplete list" suggests that there isn't one, but it's actually because the OEIS entry is restricted to numbers over 100
The full tag implies that there is a proof out there somewhere, but the page doesn't supply one
I have seen a similar problem but then all the substrings had to be prime
This is actually quite easy to bruteforce
note that each substring longer than 2 has to be an element of the sequence. This means if no number exists of length n, no element will exist of length n+1 either. So all you have to do to prove those are all the numbers is check every number of length 5.