Count only repeated

Count of only repeated elements in a sorted array of consecutive elements using binary search

# Python3 program to find the
# only repeated element and
# number of times it appears
 
# Assumptions : vector a is sorted,
# max-difference of two adjacent
# elements is 1
 
 
def sequence(a):
    if (len(a) == 0):
        return [0, 0]
 
    s = 0
    e = len(a) - 1
    while (s < e):
        m = (s + e) // 2
 
        # if a[m] = m + a[0], there is no
        # repeating character in [s..m]
        if (a[m] >= m + a[0]):
            s = m + 1
 
        # if a[m] < m + a[0], there is a
        # repeating character in [s..m]
        else:
            e = m
    return [a[s], len(a) - (
        a[len(a) - 1] - a[0])]
 
 
# Driver code
if __name__ == "__main__":
    p = sequence([1, 2, 3, 4, 4, 4, 5, 6])
 
    # Function call
    print("Repeated element is", p[0],
          ", it appears", p[1], "times")