My first solution was

print("".join(["".join([str(x) for x in range(1,i)]),str(i),"".join([str(y) for y in range(i-1,0,-1)])]))

After, I was hit with the hidden constraint cant use str(). So I went with

print(sum([x * 10**((1 + (i - 1)*2)-x) + x * 10**(x-1) for x in range(1,i)]) + i * 10**(i-1))

And that returned “you can only use one for loop” …. 😡 But the posted solution

print((10 ** i // 9) ** 2)

Is really elegant so I’m glad to have come to this discussion page.