def recaman(n):
    if n == 0:
        srn = [0]
    else:
        srn_1 = recaman(n-1)
        an = srn_1[-1] - n
        if an > 0 and an not in srn_1:
            pass
        else:
            an = srn_1[-1] + n
        srn = srn_1
        srn.append(an)
    return srn