Combinatorics Calculator

Special Numbers

• Catalan numbers
• Stirling numbers (first and second kind)
• Bell numbers
• Derangements

Advanced Techniques

• Lucas theorem (for large n, small p)
• Inclusion-exclusion
• Burnside's lemma
• Generating functions

Input Schema

{
  "type": "object",
  "properties": {
    "operation": {
      "type": "string",
      "enum": ["nCr", "nPr", "factorial", "catalan", "stirling", "lucas", "precompute"]
    },
    "n": { "type": "integer" },
    "r": { "type": "integer" },
    "mod": { "type": "integer" },
    "precomputeLimit": { "type": "integer" }
  },
  "required": ["operation"]
}

Output Schema

{
  "type": "object",
  "properties": {
    "success": { "type": "boolean" },
    "result": { "type": "integer" },
    "code": { "type": "string" },
    "formula": { "type": "string" }
  },
  "required": ["success"]
}