A052200[1] lists the number of possible Turing machines and it agrees with you. I found no sequence containing 6561 and either "Turing" or "beaver" that illumi

A052200[1] lists the number of possible Turing machines and it agrees with you. I found no sequence containing 6561 and either "Turing" or "beaver" that illuminated me to where that number came from. 1: https://oeis.org/A052200 https://oeis.org/A052200