Thanks for the feedback! You're welcome!

Oh I see it now, I knew I was missunderstanding something in the explanation

Thank you for throwing some light here :)

No. The digits of a number raised to a certain power should give the number itself. If 135 were a number of this set you should encounter an n, such that 1^n + 3^n + 5^n should be equal to 135. There is not such integer n to fulfill this equality.

But:
1^3 + 3^3 + 5^3 == 1^3 + 5^3 + 3^3

So 153 and 135 match it

135 does not fulfill the property explained.

1^3 + 3^3 + 5^3 = 153 ≠ 135

I maybe am not understanding something in the details of this problem, but why 153 is valid but not 135?