list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]nth_item = 3str_list = [    '{}\t\n'.format(m)    if(((list.index(m) + 1) % nth_item) == 0)    else    '{}\t'.format(m)    for m in list]print('\n'.join(str_list))