How can I use an rng so that each number that is generated is with a seed that ascends?

I want to use an lfsr to generate a kind of 2d random terrain, where you introduce the xy coordinate to the rng and it takes you the height of the terrain at that point, of course if you use an lfsr, the terrain will be generated with a slightly random pattern , rather linear. How can I modify the x coordinate to introduce it to the rng as a seed and make the pattern random?

I have tried to use trigonometric functions multiplying by x but I don't know if it is the best.