unique_seq_generator.py

#!/usr/bin/python

def de_bruijn(alphabet, n):
    a = [0] * len(alphabet) * n
    sequence = []

    def db(t, p):
        if t > n:
            if n % p == 0:
                sequence.extend(a[1:p + 1])
        else:
            a[t] = a[t - p]
            db(t + 1, p)
            for j in range(a[t - p] + 1, len(alphabet)):
                a[t] = j
                db(t + 1, t)
    db(1, 1)
    return "".join(alphabet[i] for i in sequence)

print(de_bruijn("0123456789abcdef", 4))