He almost certainly used some env with good entropy, he obviously knew what he was doing. Zero chance that these random numbers have a weakness on PRNG side.
Can entropy formula use for calculate position zone of puzzle
No it can not. The random number generator gathers environmental noise from device drivers and other sources into an entropy pool. That's the beauty of the entropy pool, values are not calculated, instead they are measured, emulating what hardware random number generators do, best and expensive hardware generators measure radiation sources which are totally random. Since you do not hardware random generator in normal PC/server, usually temperature variations are used instead.