I asked on Mathematica, but then understood that I used a wrong site for this question, so I asked the same question on Mathematics, not aware that it was migrated from Mathematica.
So now I have 2 copy of the same question:
I tried to delete migrated, but can't because it has answer, and I accepted it, because it's valid for Mathematica.
So, I think migrated question should be or deleted or migrated back.
Second question has 2 useful answers, so it should remain here.