An autogram is a sentence that correctly counts its own letters. Writing one is hard, because every number you write adds letters: fix the count of e’s and you have changed the count of e’s. Below, your browser is looking for some, live.
Each square: what the sentence says / what it has. Point at a letter, or at a phrase in the sentence, to light up every copy and count them yourself.
Every one of these says exactly how many of each letter it contains. The first few were found while I was making this page; any found in your browser are added at the top. Press check to put one on the sheet and count.
A draft sentence names a number for every letter. Count the letters it really has, and you get a second list of numbers. Wherever the two disagree, the search replaces the claim with the real count, but only for a random quarter of the wrong letters at a time. Changing everything at once tends to swing back and forth forever; changing a few at a time lets the sentence wander until, now and then, every number lands on itself.
Ten letters (a, b, c, d, j, k, m, p, q, z) never appear in any number word, so their counts are settled before the search starts. The other sixteen push on each other: writing seventeen adds four e’s, two n’s, an s, a v and a t, and every one of those counts then needs rewriting. Some openings have several true completions. Some seem to have none, and a search like this one can’t prove that none exists. It can only fail to find one.
The name autogram and the first serious hunts for them belong to Lee Sallows, who in the 1980s built a dedicated machine to search for them. Douglas Hofstadter wrote about self-referential sentences like these in his Scientific American columns.