Self doubt

Question

minimum mod bimary up counter which counts {0,1,8,64}

Comments

@Vikas Verma

but they didn't specify that " the output of the counter as an input  "

moreover, did you have any standard reference for it?

---

Mentioning the sequence specifically usually indicates that it is necessarily supposed to be that way.
Otherwise it would've been much easier to say Mod4 counter and writing the sequence will make a little sense.
And, no such standard reference but just experience.

---

Not sure if you'll find this convincing, but still,
https://ti.uni-due.de/ti/en/education/teaching/ws1617/fce1/material/notesErratum1.pdf

Answer 1

for designing consider the largest data in the input it is 64

for representing 64 7 bits is needed so  mod 7