Recognizing a Language

This machine will match strings of the form {a
: n
0}.
q₁ is the only final state.
current  |  symbol  |  symbol   |             |  next
state    |  read    |  written  |  direction  |  state
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Find the left end of the input
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  q0     |    a     |     a     |      L      |   q0
  q0     |    b     |     b     |      L      |   q0
  q0     |    #     |     #     |      R      |   q1
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Erase the 'a' at the left end of the input
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  q1     |    a     |     #     |      R      |   q2
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Find the right end of the input
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  q2     |    a     |     a     |      R      |   q2
  q2     |    b     |     b     |      R      |   q2
  q2     |    #     |     #     |      L      |   q3
------------------------------------------------------
Erase the 'b' at the left end of the input
------------------------------------------------------
  q3     |    b     |     #     |      L      |   q0