E053: Inverse totient multiplicities

Preview figure for E053

Tags: number-theory, quantitative-exploration, visualization, arithmetic-functions, totient, search See: Valid Tags.

Highlights

  • Compute \(\varphi(n)\) for \(n\le N\) and count how many preimages each value has.

  • Plot the histogram of multiplicities and list the top collisions.

Goal

Empirically study the many-to-one nature of the totient function.

Background (quick refresher)

Research question

For \(n\le N\), how large can the multiplicity of a totient value get, and what do the maximizers look like?

Method

  • Compute \(\varphi(n)\) on a range and build a frequency table for values.

  • Visualize multiplicities (histogram) and inspect the most frequent values.

How to run

  • make run EXP=e053

  • uv run python -m mathxlab.experiments.e053

Outputs

This experiment follows the standard output contract:

  • out/e053/figures/ — generated figures (PNG)

  • out/e053/report.md — short narrative report

  • out/e053/manifest.json — snapshot metadata for the gallery

Published run snapshot

If this experiment is included in the docs gallery, include the published snapshot (report + params).

  • n_max: 200000

Top 10 totient values by multiplicity (count, m):

  • 357 x : m = 40320

  • 332 x : m = 51840

  • 331 x : m = 34560

  • 320 x : m = 60480

  • 307 x : m = 43200

  • 291 x : m = 48384

  • 281 x : m = 30240

  • 280 x : m = 47520

  • 280 x : m = 46080

  • 276 x : m = 25920

Figure:

  • fig_01_multiplicity_hist.png

params.json (snapshot)
{
  "hist_max": 40,
  "n_max": 200000
}

References

See Apostol [1976], Niven et al. [1991].