Language accepted is anb3n : n $\geq$ 0
Foe ex. L = aabbbbbb.
First a = X and move right untill first b occurred.
make 3 consecutive b's = Y and directed back to left. (at this case L = BXaYYYbbbB)
now skip all Y as it is and all a's as it is and reach until X occurs.
Repeat the step for 2nd 'a' again.
and Finally when you come back and see X and immediate Y then again traverse through all Y's and accept the language.
If any extra b occurred then it won't reach to Blank state.
