Oeis MCP Server

by cyanheads Your server? Claim it

answering

Oeis MCP Server is answering right now. Last checked 14 min ago. 108 installs a week from npm. It exposes 6 tools. Last commit 18 Oct 2026.

Identify integer sequences by terms, search the OEIS, read formulas, programs, b-files, cross-refs.

Installs per day peak 218 · avg 27 · -56% w/w

a month agotoday

Uptime history 31 days of history · worst day 98%

31 days agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

594 ms

Response time

average over 24h

108

Installs / week

npm and PyPI

What changed 4

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 18 October 2026. No other catalogue keeps this.

18 Oct 2 tools changed the parameters they ask for oeis_get_terms, oeis_search_sequences

18 Oct a tool description was rewritten oeis_get_terms

18 Oct a tool changed version

Nothing serious here today

Today is the operative word: we check Oeis MCP Server every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 14 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add oeis-mcp-server --transport http https://oeis.caseyjhand.com/mcp

Settings → Connectors → Add custom connector, then paste this address

https://oeis.caseyjhand.com/mcp

~/.codex/config.toml

[mcp_servers.oeis-mcp-server]
url = "https://oeis.caseyjhand.com/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "oeis-mcp-server": {
      "url": "https://oeis.caseyjhand.com/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "oeis-mcp-server": {
      "type": "http",
      "url": "https://oeis.caseyjhand.com/mcp"
    }
  }
}

Available tools 6

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

oeis

oeis_get_cross_refs

List sequences related to an OEIS entry. direction outgoing returns the A-numbers named in the entry's cross-reference (Cf.) lines, with any parenthetical note beside each; direction incoming returns entries that mention this A-number anywhere. Each row carries the related sequence's name and first terms. 10 rows per page.

oeis_get_sequence

Fetch one OEIS entry by A-number. Returns the name, data-line terms, offset, keywords, author, dates, and the sections: comments, formulas (recurrences and generating functions), examples, programs (Maple, Mathematica, PARI, Python, …), references, links, cross-references, and extensions. When the sections together exceed 24,000 characters of serialized JSON, the core fields come back with a section outline instead; call again with sections to pick what to read. A selection past 100,000 bytes comes back in parts cut between items: pass nextFromItem as fromItem, with the same sections, for the next part.

oeis_get_terms

List terms a(n) of a sequence with their indices n. Reads the entry's b-file when it has one — often thousands of terms beyond the data line — and otherwise the data line itself. Values are exact decimal strings of any size. A slice stops at limit terms (at most 1000 per call), at about 100,000 bytes, or at the end of one 1 MiB part of a larger b-file, whichever comes first; nextFromIndex continues it.

oeis_identify_sequence

Identify integer sequences that contain a run of consecutive terms, e.g. "1, 2, 5, 14, 42". Returns up to 10 matches per page in OEIS relevance order, each with the index n at which the supplied run begins. For the best hit rate supply about 6 terms and leave off the first one or two, since sources disagree on where a sequence starts. OEIS matches only the first terms of each entry (its data line, at most about 270 characters), not its b-file, so a run from far into a sequence is not found. Takes up to 60 terms, each an integer of at most 200 digits or the wildcard _ for one unknown term.

oeis_list_reference

Look up OEIS vocabulary used by the other tools: keyword flags (nonn, core, tabl, cons, …), search syntax (prefixes, operators, wildcards, sort orders, paging window), and identifier conventions (A-numbers, legacy M/N numbers, offsets, b-files).

oeis_search_sequences

Search the OEIS using its query syntax: plain words, "quoted phrases", comma-separated terms, prefixes (keyword:, author:, name:, comment:, formula:, program:, xref:, id:), | for OR, and a leading - to exclude. Returns up to 10 summaries per page. For identifying a sequence from its terms, oeis_identify_sequence is the direct route.

Endpoints

URL	Transport	State	Latency	Checked
https://oeis.caseyjhand.com/mcp	streamable-http	answering	578 ms	14 min ago

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Oeis MCP Server — questions

Answers built from our own checks of this server.

What can Oeis MCP Server do?

It exposes 6 tools, read directly from the server on our last check. Among them: oeis_get_cross_refs, oeis_get_sequence, oeis_get_terms, oeis_identify_sequence, oeis_list_reference, oeis_search_sequences. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is Oeis MCP Server working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 594 ms. The bar chart above shows every period we have measured.

How do I connect Oeis MCP Server?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does Oeis MCP Server need an API key?

No. Oeis MCP Server completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 6 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is Oeis MCP Server?

It answers our handshake in 594 ms on average, which is faster than 19% of all working MCP servers we measure. That is on the slow side — worth knowing if the tool sits inside an interactive loop. The comparison comes from our own checks across the whole registry, every 15 minutes.

How many people use Oeis MCP Server?

The npm package @cyanheads/oeis-mcp-server was installed 108 times in the last week. Week over week that is -56%. We show installs rather than GitHub stars on purpose: a star is a bookmark, an install is someone actually running it.

Is Oeis MCP Server open source?

The code is open source: it is published under the Apache-2.0 licence, written in TypeScript, 1 stars on GitHub and 1 open issue. The licence covers the code in the repository, not the hosted service at oeis.caseyjhand.com, which runs on its operator's own terms.