Permutations (nPr)
combinatorics.openverbs.com · 5 paid endpoints · listed 2026-10-27
Binomial coefficient nCr = n!/(r!(n-r)!), the number of unordered r-subsets of n. Requires r ≤ n and min(r, n-r) ≤ 10000.
Paid endpoints
| Method | Endpoint | Price | Networks |
|---|---|---|---|
| POST | combinatorics.openverbs.com/v1/catalan The n-th Catalan number Cₙ = C(2n, n)/(n+1), counting balanced bracketings, binary trees, and many other structures. Requires n ≤ 10000. | $0.004 | Base |
| POST | combinatorics.openverbs.com/v1/combinations Binomial coefficient nCr = n!/(r!(n-r)!), the number of unordered r-subsets of n. Requires r ≤ n and min(r, n-r) ≤ 10000. | $0.004 | Base |
| POST | combinatorics.openverbs.com/v1/factorial Exact factorial n! for 0 ≤ n ≤ 20000, returned as a decimal string with its digit count. | $0.004 | Base |
| POST | combinatorics.openverbs.com/v1/multinomial Multinomial coefficient (k1+k2+…)! / (k1! k2! …) — the number of ways to partition n = Σki items into labelled groups of the given sizes. The sum must be ≤ 2000 | $0.004 | Base |
| POST | combinatorics.openverbs.com/v1/permutations Number of ordered arrangements of r items from n, nPr = n!/(n-r)!. Requires r ≤ n and r ≤ 10000. | $0.004 | Base |
Latest checks
| When | Endpoint | HTTP | ms | Result |
|---|---|---|---|---|
| 5 days ago | combinatorics.openverbs.com/v1/catalan | 402 | 592 | valid x402 v2 terms |
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