Package 'oeis.tools'

OEIS B-file Class

Description

OEIS B-file Class

Usage

BFile(oeis_id)

Arguments

oeis_id

Character string (e.g., "A000045") Downloads the b-file (list of ⁠n a(n)⁠ pairs) of an OEIS sequence. If the download or parsing fails, a warning is issued and the object holds no data.

Value

An object of class "BFile"

Examples

primes <- BFile("A000040")
primes

---

Check if an OEIS ID is valid

Description

Validates that the OEIS ID follows the format: A followed by exactly 6 digits

Usage

check_id(oeis_id)

Arguments

oeis_id

Character string to validate

Value

Logical TRUE if valid, FALSE otherwise

Examples

check_id("A000045")  # TRUE
check_id("invalid")  # FALSE

---

Create a b-file text file for an OEIS sequence

Description

Writes sequence values in the standard b-file format ("n a(n)", one pair per line).

Usage

create_bfile(oeis_id, data, offset = 1L, output_path)

Arguments

oeis_id	Character string (e.g., "A213676")
data	Vector of sequence values (numeric, integer, character, or gmp::bigz)
offset	Integer starting index. Defaults to 1
output_path	Directory or exact file path to save the b-file. When a directory is given, the standard b-file name (e.g., "b213676.txt") is used inside it

Value

Character string: the path to the created b-file

Examples

path <- create_bfile("A000045", c(0, 1, 1, 2, 3, 5, 8), offset = 0,
                     output_path = tempdir())
readLines(path)
unlink(path)

---

Extract OEIS IDs from text

Description

Extract OEIS IDs from text

Usage

extract_oeis_ids(text)

Arguments

text	Character string to search

Value

Character vector of OEIS IDs

Examples

extract_oeis_ids("Cf. A000045, A000032 and A000045.")

---

Get B-file Data

Description

Get B-file Data

Usage

get_bfile_data(bfile)

Arguments

bfile

A BFile object

Value

A gmp::bigz vector or NULL

Examples

primes <- BFile("A000040")
head(get_bfile_data(primes))

---

Get B-file Indices

Description

Get B-file Indices

Usage

get_bfile_indices(bfile)

Arguments

bfile

A BFile object

Value

Integer vector of the first-column indices, or NULL when parsing failed

Examples

primes <- BFile("A000040")
head(get_bfile_indices(primes))

---

Get B-file Information

Description

Get B-file Information

Usage

get_bfile_info(seq)

Arguments

seq	A Sequence object

Value

List with b-file metadata: available, filename, url, length, first, last, min, max

Examples

fib <- Sequence("A000045")
get_bfile_info(fib)

---

Build a BibTeX @misc entry citing this OEIS sequence

Description

Build a BibTeX @misc entry citing this OEIS sequence

Usage

get_bibtex(seq)

Arguments

seq	A Sequence object

Value

Character string with a BibTeX ⁠@misc⁠ entry

Examples

fib <- Sequence("A000045")
cat(get_bibtex(fib))

---

Return the parsed sequence data terms

Description

Return the parsed sequence data terms

Usage

get_data_values(seq)

Arguments

seq	A Sequence object

Value

A gmp::bigz vector of terms

Examples

fib <- Sequence("A000045")
get_data_values(fib)[1:10]

---

Get B-file Filename

Description

Get B-file Filename

Usage

get_filename(bfile)

Arguments

bfile

A BFile object

Value

Character string

Examples

primes <- BFile("A000040")
get_filename(primes)

---

Retrieve the OEIS graph image for display

Description

Uses IRdisplay::display_png() when running inside a Jupyter/IRkernel session; otherwise returns the raw PNG bytes.

Usage

get_graph_image(
  seq,
  width = NULL,
  height = NULL,
  timeout = 10,
  use_cache = TRUE
)

Arguments

seq	A Sequence object
width	Optional display width in pixels
height	Optional display height in pixels
timeout	Numeric timeout in seconds
use_cache	Logical; reuse a previously downloaded PNG when TRUE

Value

Raw vector of PNG bytes (invisibly, when displayed via IRdisplay)

Examples

fib <- Sequence("A000045")
img <- get_graph_image(fib)

---

Download the OEIS graph image as PNG bytes

Description

Download the OEIS graph image as PNG bytes

Usage

get_graph_png(seq, timeout = 10, use_cache = TRUE)

Arguments

seq	A Sequence object
timeout	Numeric timeout in seconds
use_cache	Logical; reuse a previously downloaded PNG when TRUE (default)

Value

Raw vector of PNG bytes

Examples

fib <- Sequence("A000045")
png_bytes <- get_graph_png(fib)
length(png_bytes)

---

Return the OEIS keyword description for a given tag

Description

Instance-method wrapper around oeis_keyword_description().

Usage

get_keyword_description(seq, keyword_tag)

Arguments

seq	A Sequence object
keyword_tag	Character string

Value

Character string with description, or NULL

Examples

fib <- Sequence("A000045")
get_keyword_description(fib, fib$keyword[1])

---

Get B-file URL

Description

Get B-file URL

Usage

get_url(bfile)

Arguments

bfile

A BFile object

Value

Character string

Examples

primes <- BFile("A000040")
get_url(primes)

---

Extract cross-reference IDs

Description

Extract cross-reference IDs

Usage

get_xref_ids(seq)

Arguments

seq	A Sequence object

Value

Character vector of unique OEIS IDs, in first-seen order

Examples

fib <- Sequence("A000045")
head(get_xref_ids(fib))

---

Check whether the OEIS web service is reachable

Description

Sends a small request to the OEIS search API. Useful to guard code that needs the network, since the OEIS may be down or may refuse requests from some hosts (for example, cloud or continuous-integration servers).

Usage

oeis_available(timeout = 5)

Arguments

timeout

Numeric timeout in seconds

Value

TRUE if the OEIS answered successfully, FALSE otherwise

Examples

oeis_available()

---

Generate OEIS b-file filename

Description

Generate OEIS b-file filename

Usage

oeis_bfile(oeis_id)

Arguments

oeis_id

Character string (e.g., "A000045")

Value

Character string (e.g., "b000045.txt")

Examples

oeis_bfile("A000045")

---

Get OEIS keyword description

Description

Get OEIS keyword description

Usage

oeis_keyword_description(keyword_tag)

Arguments

keyword_tag

Character string

Value

Character string with description or NULL

Examples

oeis_keyword_description("core")
oeis_keyword_description("nonn")

---

Plot B-file Data

Description

Plot B-file Data

Usage

plot_data(bfile, n = NULL, plot_style = "line", ...)

## S3 method for class 'BFile'
plot_data(
  bfile,
  n = NULL,
  plot_style = "line",
  p = NULL,
  show = TRUE,
  return_plot = FALSE,
  ...
)

Arguments

bfile	A BFile object
n	Number of leading points to plot. When NULL (default), all available points are plotted
plot_style	One of "line" (default), "joined" (alias for "line"), or "scatter"
...	Additional aesthetic parameters forwarded to geom_line() or geom_point()
p	An existing ggplot object to layer onto, or NULL to create a new plot
show	Logical; print the plot when TRUE (default)
return_plot	Logical; return the ggplot object when TRUE. Defaults to FALSE

Value

A ggplot2 plot object when return_plot = TRUE; otherwise invisible NULL

Examples

primes <- BFile("A000040")
plot_data(primes, n = 100, plot_style = "scatter")
g <- plot_data(primes, n = 100, show = FALSE, return_plot = TRUE)

---

Plot Sequence Data

Description

Prefers the sequence's embedded b-file (richer, longer) and falls back to the terms parsed from the OEIS JSON entry.

Usage

## S3 method for class 'Sequence'
plot(x, ...)

Arguments

x	A Sequence object
...	Additional arguments passed to plot_data()

Value

The value returned by plot_data(): a ggplot object when return_plot = TRUE, otherwise invisible NULL

Examples

fib <- Sequence("A000045")
plot(fib, n = 50)

---

OEIS Sequence Class

Description

OEIS Sequence Class

Usage

Sequence(oeis_id)

Arguments

oeis_id

Character string (e.g., "A000045")

Value

An object of class "Sequence"

Fetches an OEIS entry (and its b-file) over the internet.

Examples

fib <- Sequence("A000045")
fib$name

---