R Package oeis.tools on CRAN

1 Introduction

oeis.tools is an R package to query the On-Line Encyclopedia of Integer Sequences (OEIS) from R code. It is the R counterpart of the Python oeis-tools project, and version 0.3.1 is now available on CRAN, so it no longer has to be installed from GitHub.

👉 https://CRAN.R-project.org/package=oeis.tools

2 Installation

Requires R ≥ 4.1.0.

install.packages("oeis.tools")
library(oeis.tools)

3 Examples

3.1 Reading a sequence

Sequence() downloads the OEIS entry of a sequence and exposes its fields (name, keywords, formulas, programs, cross-references…):

fib <- Sequence("A000045")

fib$name
#> [1] "Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1."

fib$keyword
#> [1] "nonn"    "core"    "nice"    "easy"    "hear"    "changed"

3.2 Cross-references and citations

get_xref_ids() returns the A-numbers cited in the %Y lines of the entry, and get_bibtex() builds a BibTeX record ready to paste into a paper:

head(get_xref_ids(fib))
#> [1] "A001622" "A039834" "A001519" "A001906" "A001690" "A000213"

cat(get_bibtex(fib))
#> @misc{A000045,
#>   author       = {N. J. A. Sloane},
#>   title        = {A000045: Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1.},
#>   howpublished = {The {O}n-{L}ine {E}ncyclopedia of {I}nteger {S}equences},
#>   year         = {1991},
#>   ...
#>   url          = {https://oeis.org/A000045}
#> }

3.3 Downloading and plotting b-files

BFile() downloads the b-file of a sequence (the long list of terms), and plot_data() draws it with ggplot2. With return_plot = TRUE it returns the plot object, so it can be themed and saved like any other ggplot:

library(ggplot2)

psi <- BFile("A001615")

p <- plot_data(psi, n = 1000, plot_style = "scatter",
              show = FALSE, return_plot = TRUE,
              color = "#1f6fb2", size = 0.8) +
  theme_minimal(base_size = 13)

ggsave("dedekind-psi-A001615.png", p, width = 7, height = 4.2, dpi = 150, bg = "white")

Scatter plot of the Dedekind psi function for n up to 1000: points fan out in straight rays from the origin, the lowest ray psi(n) = n + 1 formed by the primes — Dedekind psi function $\psi(n) = n \prod_{p \mid n} (1 + 1/p)$ (A001615) for $n \le 1000$, plotted with `plot_data()`

The points fall on rays through the origin: the lowest one, $\psi(p) = p + 1$, is made of the primes, and the steeper rays collect the numbers that share the same set of small prime factors.

4 Arbitrary precision

Terms are stored as gmp::bigz integers, so sequences whose values grow beyond $2^{53}$, the largest range where a double represents every integer exactly, keep all their digits:

head(get_bfile_data(psi))
#> Big Integer ('bigz') object of length 6:
#> [1] 1  3  4  6  6  12

When the terms are too large to convert to numbers, plot_data() switches to a $\operatorname{sign}(a_n)\log_{10}|a_n|$ scale automatically.

5 Main functions

Function	Purpose
`Sequence()`	Download an OEIS entry and its fields
`BFile()`	Download the b-file (terms) of a sequence
`get_xref_ids()`	A-numbers cross-referenced by a sequence
`get_bibtex()`	BibTeX citation of a sequence
`plot_data()`	Plot the terms of a b-file with `ggplot2`

6 License

The package is distributed under the MIT License. OEIS content is available under the OEIS End-User License Agreement (CC BY-SA 4.0).

7 Links

--- title: R Package oeis.tools on CRAN description: Work with OEIS integer sequences from R, now on CRAN author: 'Enrique Pérez Herrero' date: '2026-10-13' image: 'dedekind-psi-A001615.png' image-alt: "Scatter plot of the Dedekind psi function (OEIS A001615) for n up to 1000, made with oeis.tools" categories: - R - Package - Mathematics - OEIS editor: source lang: en draft: false engine: markdown --- [![CRAN status](https://www.r-pkg.org/badges/version/oeis.tools)](https://CRAN.R-project.org/package=oeis.tools) [![R ≥ 4.1.0](https://img.shields.io/badge/R-%E2%89%A5%204.1.0-276dc3)](https://www.r-project.org/) [![License: MIT](https://img.shields.io/badge/license-MIT-green)](https://github.com/oeistools/oeis-tools-R/blob/main/LICENSE) ## Introduction `oeis.tools` is an R package to query the [On-Line Encyclopedia of Integer Sequences](https://oeis.org) (OEIS) from R code. It is the R counterpart of the Python [`oeis-tools`](https://github.com/oeistools/oeis-tools) project, and version **0.3.1** is now available on **CRAN**, so it no longer has to be installed from GitHub. 👉 https://CRAN.R-project.org/package=oeis.tools --- ## Installation Requires **R ≥ 4.1.0**. ```r install.packages("oeis.tools") library(oeis.tools) ``` --- ## Examples ### Reading a sequence `Sequence()` downloads the OEIS entry of a sequence and exposes its fields (name, keywords, formulas, programs, cross-references…): ```r fib <- Sequence("A000045") fib$name #> [1] "Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1." fib$keyword #> [1] "nonn" "core" "nice" "easy" "hear" "changed" ``` ### Cross-references and citations `get_xref_ids()` returns the A-numbers cited in the `%Y` lines of the entry, and `get_bibtex()` builds a BibTeX record ready to paste into a paper: ```r head(get_xref_ids(fib)) #> [1] "A001622" "A039834" "A001519" "A001906" "A001690" "A000213" cat(get_bibtex(fib)) #> @misc{A000045, #> author = {N. J. A. Sloane}, #> title = {A000045: Fibonacci numbers: F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1.}, #> howpublished = {The {O}n-{L}ine {E}ncyclopedia of {I}nteger {S}equences}, #> year = {1991}, #> ... #> url = {https://oeis.org/A000045} #> } ``` ### Downloading and plotting b-files `BFile()` downloads the b-file of a sequence (the long list of terms), and `plot_data()` draws it with `ggplot2`. With `return_plot = TRUE` it returns the plot object, so it can be themed and saved like any other `ggplot`: ```r library(ggplot2) psi <- BFile("A001615") p <- plot_data(psi, n = 1000, plot_style = "scatter", show = FALSE, return_plot = TRUE, color = "#1f6fb2", size = 0.8) + theme_minimal(base_size = 13) ggsave("dedekind-psi-A001615.png", p, width = 7, height = 4.2, dpi = 150, bg = "white") ``` ![Dedekind psi function $\psi(n) = n \prod_{p \mid n} (1 + 1/p)$ (A001615) for $n \le 1000$, plotted with `plot_data()`](dedekind-psi-A001615.png){fig-alt="Scatter plot of the Dedekind psi function for n up to 1000: points fan out in straight rays from the origin, the lowest ray psi(n) = n + 1 formed by the primes" fig-align="center"} The points fall on rays through the origin: the lowest one, $\psi(p) = p + 1$, is made of the primes, and the steeper rays collect the numbers that share the same set of small prime factors. --- ## Arbitrary precision Terms are stored as `gmp::bigz` integers, so sequences whose values grow beyond $2^{53}$, the largest range where a `double` represents every integer exactly, keep all their digits: ```r head(get_bfile_data(psi)) #> Big Integer ('bigz') object of length 6: #> [1] 1 3 4 6 6 12 ``` When the terms are too large to convert to numbers, `plot_data()` switches to a $\operatorname{sign}(a_n)\log_{10}|a_n|$ scale automatically. --- ## Main functions | Function | Purpose | | --- | --- | | `Sequence()` | Download an OEIS entry and its fields | | `BFile()` | Download the b-file (terms) of a sequence | | `get_xref_ids()` | A-numbers cross-referenced by a sequence | | `get_bibtex()` | BibTeX citation of a sequence | | `plot_data()` | Plot the terms of a b-file with `ggplot2` | ## License The package is distributed under the [MIT License](https://github.com/oeistools/oeis-tools-R/blob/main/LICENSE). OEIS content is available under the [OEIS End-User License Agreement](https://oeis.org/LICENSE) (CC BY-SA 4.0). ## Links - [CRAN - oeis.tools](https://CRAN.R-project.org/package=oeis.tools) - [GitHub - oeistools/oeis-tools-R](https://github.com/oeistools/oeis-tools-R) - [GitHub - oeistools/oeis-tools (Python)](https://github.com/oeistools/oeis-tools) - [The On-Line Encyclopedia of Integer Sequences](https://oeis.org)