Primary key with randomly varying increments (so it cannot be guessed easily)

I would like the primary keys to be auto-incremented and generated but in varying increments. For ex, if I have increment range as 100... then the auto generated keys would be something like below: - 20 (random number between 1 and 100) - 30 (add random number 10 that's between 1 and 100) - 113 (add random number 83 that's between 1 and 100) - 118 (add random number 5 that's between 1 and 100) - 217 (add random number 99 that's between 1 and 100) - 220 (add random number 3 that's between 1 and 100) The data domains are often exposed via HTTP REST endpoints, and I would like the end users to not able to guess the primary keys by simply incrementing numbers. I'm trying to avoid UUID/GUIDs if possible. My REST URLs are longer, often with parent-child identifiers. (Yes, it's avoidable but I prefer it for simpler testing/troubleshooting). So I prefer numbers as identifiers. Is there any simpler solution that I'm not aware of? I'm using PostgreSQL but any generic solution is also fine.