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combinatorics.openverbs.com v1 catalan
https://combinatorics.openverbs.com/v1/catalan
answers 402
The n-th Catalan number Cā = C(2n, n)/(n+1), counting balanced bracketings, binary trees, and many other structures. Requires n ā¤ 10000.
We sent a real
POST request to this endpoint and it
answered 402 with payment requirements we could parse.
- Price
- $0.004
- Network
- base
- Pay to
- 0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A
- Spec dialect
- v2 (declares x402Version 2)
- Transport
- PAYMENT-REQUIRED header
- HTTP method
- POST
- Response latency
- 255 ms
- Payment options
- 1 usable of 1
- Last checked
- 2026-09-06T01:20:10.478Z (23d ago)
- Category
- finance-crypto
Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fcombinatorics.openverbs.com%2Fv1%2Fcatalan"