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Factorial for Agents
x402
Factorial for Agents is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).
Computes n! (factorial) for integer n up to 20, returning the exact result or a structured error for out-of-range inputs, billed at $0.001 USDC per successful call via x402 on Base.
Price / call$0.001
Success—
StatusUnknown
How this service works
Factorial (n≤20). Call for combinatorics demos and small counting problems with an explicit n cap. Returns n! for n up to 20; larger n returns a structured error. $0.001 USDC per successful call via x402 on Base—deterministic first-party JSON, no API key, no subscription, and nothing is billed on structured validation errors.
Output
Returns a JSON object containing the computed factorial value (n!) as an integer for valid inputs (0 ≤ n ≤ 20). For n > 20 or invalid inputs, returns a structured JSON error indicating the out-of-range condition. Successful calls are billed $0.001 USDC; structured validation errors are not billed.
Example use cases
Combinatorics calculation in a pipeline
“I need to know how many ways I can arrange 8 items — can you compute 8 factorial for me?”
Education demo for permutations
“Show me the factorial of 5 so I can explain permutations to my students.”
Sanity check fixture in test suite
“Give me the exact value of 20 factorial so I can use it as a test fixture to verify my own math library.”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/factorialWhen to prefer
Choose this endpoint when you need a deterministic, first-party factorial computation without shipping a math library or managing dependencies. Ideal for agentic pipelines, combinatorics demos, test fixtures, or educational tools where n is guaranteed to be 20 or below and you want a pay-per-call model with no API key or subscription overhead.
Side effects
- n > 20: returns a structured error indicating n exceeds the allowed cap, no charge
- n < 0: returns a structured validation error for negative input
- non-integer n: schema validation error, not billed
- missing n field: structured validation error, not billed
- payment failure: x402 payment rejected, call not executed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| n | integer | Integer input (see tool summary for allowed range). |
Output
Schema · Response
{
"type": "json",
"example": {
"n": 12,
"value": 479001600,
"schema": "delx/factorial/v1"
}
}Tags
x402
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