Minecraft wiki entry for Placed_feature, associated text: noise_based_count—Returns multiple copies of the current block position. The count is based on a noise value at the current block position. It can gradually change based on the noise value. The count is calculated by ceil((noise(x / noise_factor, z / noise_factor) + noise_offset) * noise_to_count_ratio).
 noise_factor: Scales the noise input horizontally. Higher values make for wider and more spaced out peaks.
 noise_offset: (optional) Offset of the "positive" area, where features are generated. Can affect the count if above 0. Defaults to 0.
 noise_to_count_ratio: Count multiplier, provided any features are generated.