def integers_to_nucleotides(int_seq):
    """Converts a integer sequence to an nucleotide representation.

    The base characters in the integer string (0, 1, 2 and 3) are converted to the following: 0 -> A, 1 -> C, 2 -> G
    and 3 -> T. The combined string is returned.

    Parameters
    ----------
    int_seq : str
        A integer sequence string.

    Returns
    -------
    str
        The nucleotide representation string for the given integer sequence.

    """
    nuc_sequence = []
    for i in int_seq:
        if int(i) == 0:
            nuc_sequence.append('A')
        elif int(i) == 1:
            nuc_sequence.append('C')
        elif int(i) == 2:
            nuc_sequence.append('G')
        elif int(i) == 3:
            nuc_sequence.append('T')
    return ''.join(nuc_sequence)
