[anandijain]

A bit unrelated but you posted oeis so hoping you know. In the article they mention there are 17 trillion possible 5-2 turing machines. I tried finding the sequence for this but couldn't.

I found this https://oeis.org/A141475, but it gives 27 trillion for 5.

[tromp]

While the official formula [1] is (4(n+1))^(2n) , if one ignores the symbol written and head movement for transitions to halt, then this becomes (4n+1)^(2n), which is ~ 17 trillion for n=5.

[1] https://oeis.org/A052200