Sorry to say, Claude Sonnet 4.5 (with and without extended thinking) has this one solved now. So, not “any” LLM, but maybe some still need work.

I presume they finally got around to training the internal reasoning loop into predicting when it needs to apply answer predictions character-by-character.

—- Transcripts from Claude Sonnet 4.5, initially with extended thinking:

> How many a’s in the phrase “artichokes and aardvarks”? Be sure to check your answer.

> Let me count the letter ‘a’ in “artichokes and aardvarks”: • artichokes: 1 ‘a’ (at the beginning) • and: 1 ‘a’ (at the beginning) • aardvarks: 3 ‘a’s (two at the beginning: “aa”, and one in the middle: “ardvarks”) Total: 1 + 1 + 3 = 5 ‘a’s Let me verify by marking them: artichokes and aardvarks Yes, there are 5 letter ‘a’s in the phrase “artichokes and aardvarks”.

> Are you sure that’s correct?

> Let me recount more carefully: “artichokes and aardvarks” Going through each word letter by letter: 1. artichokes - has 1 ‘a’ (first letter) 2. and - has 1 ‘a’ (first letter) 3. aardvarks - has 3 ‘a’s (first letter, second letter, and one more in the middle) Total: 1 + 1 + 3 = 5 ‘a’s Yes, I’m confident the answer is 5. Is there something specific you’d like me to recheck?

> How many r’s in strawberry?

> Let me count the letter ‘r’ in “strawberry”: s-t-r-a-w-b-e-r-r-y Going through each letter: • s: not an r • t: not an r • r: 1st r • a: not an r • w: not an r • b: not an r • e: not an r • r: 2nd r • r: 3rd r • y: not an r There are 3 r’s in “strawberry”.

<Without extended thinking> > How many u’s in universalulis?

> Looking at “universalulis” letter by letter: u-n-i-v-e-r-s-a-l-u-l-i-s There are 2 u’s in “universalulis”.