[brudgers]

  without *any* contribution

I'm not a lawyer. If I were, that phrase would give me a toehold or restless sleep depending on which side of the pile of money I was on...ok, actually if I was on the "hands on the money side", I would just advise avoiding the risk because that's what lawyers are expected to do. Or to put it another way, the argument that works created by the program are not copyrightable might tend to be more expensive than simply paying licensing fees in a business context.

But again, I'm not a lawyer.

[FigBug]

If there is a contribution from a human, then it would be from the user who entered some parameters and ran the program, not the author of program. Therefore the copyright would belong to the user, which is fine.

The only way the copyright could belong to the author of the program, is if the program contained copyrighted material that it copied directly into the output.

For example, if the program contained 1000 prewritten melodies, and randomly selected one and copied it into the output.

[brudgers]

I'm not sure there is case law to support that argument. I am not sure that there isn't case law to support it either. Even if there is case law to support it, the circumstances in which the case law is helpful are somewhat likely to be more expensive than licensing other music more explicitly providing more conventional copyright permissions. For example, assuming the premise that the copyright belongs to the user in a case where two different users enter the same (or even similar) parameters then one of their compositions is probably copyright infringing on the other author -- or both are on a third even earlier author who entered the same or similar parameters.

Again I am not a lawyer though it doesn't prevent me from thinking along the lines I have observed laywers thinking.