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The n-th Catalan number Cₙ = C(2n, n)/(n+1), counting balanced bracketings, binary trees, and many other structures. Requires n ≤ 10000.

Endpoint: https://combinatorics.openverbs.com/v1/catalan
Price: $0.004 / call
Settles via: cdp
Category: —
Last seen live: Tue, 08 Sep 2026 05:24:25 UTC
Last probed: Tue, 08 Sep 2026 05:24:25 UTC
First indexed: Tue, 08 Sep 2026 05:22:25 UTC
Sources: cdp-x402

Probe history

Last 1 probes, newest on the right. 100% answered with a payment challenge.

When	Result	Method	Status	Latency
Tue, 08 Sep 2026 05:24:25 UTC	challenge	http-402	402	844 ms

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