Inverting of Boolean variable not happening after end of every for loop I am trying to create a pattern as follows - 1 0 1 1 0 1 0 1 0 1 1 0 1 0 1 My output is - 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 My code is as follows - N=5 bool_ = True for row in range(1,N+1): for i in range(1, row+1): if i>1: print(' ', end='') print(int(bool_), end= '') bool_ = not bool_ print() Not sure what is wrong in this. It seems like something to do with range of second for loop.