CVP verified calculation capability

Integer sequences Calculation Capability

Arithmetic and geometric sequences, Fibonacci (F_0=0), and linear recurrences. Exact BigInt. Discovery pages share this capability. Not Pascal, not partition, not n!. Engine id is sequence — never arithmetic.

Math Capability ID math.sequences version 1.0.1 CVP VERIFIED STALE Core

Model

Arithmetic

Arithmetic: a_n = a + (n−1)d
Geometric: a_n = a r^{n−1}
Fibonacci: F_n = F_{n−1} + F_{n−2}

Modes: arithmetic · geometric · fibonacci · linear recurrence

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`n`	—	—	input / output
`a`	—	—	input
`d`	—	—	input
`r`	—	—	input
`p`	—	—	input
`q`	—	—	input
`a0`	—	—	input
`a1`	—	—	input
`term`	—	—	output
`value`	—	—	output
`sum`	—	—	output
`algorithm`	—	—	output
`max_n`	—	—	output

Trusted Math contract

Inspectable numeric contract for this Capability@Version. Not a rewrite of the engine.

Field	Declaration
`numeric_domain`	integer
`exactness`	exact
`algorithm`	closed AP / GP / Fibonacci (BigInt)
`valid_domain`	integer index in the published bound; GP ratio integer for exact path
`singularity_policy`	INVALID_INPUT / INVALID_MODE off the published sequence modes
`branch_policy`	not applicable — integer domain
`tolerance`	not applicable — exact integer identity
`convergence`	not applicable — non-iterative Euclidean / combinatorial
`conditioning`	not applicable — not a floating matrix
`rounding`	none — BigInt / exact integer
`overflow`	coded error or stringified BigInt when exceeding JSON number
`reproducibility`	deterministic exact integer + Capability@Version
`independent_oracle`	cvp:math.sequences O2 / Evidence published cases
`golden_vectors`	Evidence golden + boundary + property (and published_reference_case when listed)

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

The Result Card includes an engine-linked stem figure of a_k (marker is published term; at most 16 indices, window ending at n). Same closed form / recurrence as REST/MCP. Terms array is not a REST field. Huge BigInt terms omit the figure.
Integers
n ≤ 1000
Not Pascal / partition / n!

Example

One numerical check. The calculator page holds worked steps and FAQ.

mode=arithmetic a=2 d=3 n=5 → 14

Open this example in the calculator

Trust

CVP VERIFIED · production STALE · CVP protocol 1.0.0-proposed · Core assurance · all published modes. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.

CVP: CVP VERIFIED · production STALE · CVP protocol 1.0.0-proposed · Core assurance · all published modes· View Manifest · CVP overview · Specification
Verified scope: all published modes
Assurance: Core
Declared partition coverage: PASS · 5/5 declared partitions (arithmetic, geometric, fibonacci, linear-recurrence, invalid-domain)
Calculation version: 1.0.1
Verification: 12/12 calculation tests · 4/4 legacy golden · 2/2 legacy boundary · 6/6 legacy property
Production surface contract: 6/6
Versions: Calculation 1.0.1 · CVP protocol 1.0.0-proposed · Evidence 2026-10-07.signed-bigint-publication
Verification revision: 2026-10-07.signed-bigint-publication · 3/3 property · digest 0c1fda7d6011
Reference: O1 model · O2 expected_values · O2 numerical_behavior
Interfaces: PASS · UI (SSR) / REST / MCP
ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only.
CVP suite: 8/8 golden · 3/3 CVP boundary · 6/6 invalid · 3/3 property · 5/5 cross-interface · 1/1 cross-calculator · 6/6 CVP contract
Supplemental domain review: Not performed
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.0.1 (workspace artifacts agree)
Review-policy tier: Engine tested — catalog token engine_tested; supplemental; not CVP status

STALE · Build schema 1.0.1 matches page · production binding STALE · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · CVP STALE · attestation STALE — Production CURRENT withheld · Public/cache ✓ · Origin ✓

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.

curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/sequence' \
  -H 'Content-Type: application/json' \
  -d '{"inputs":{"mode":"arithmetic","a":2,"d":3,"n":5},"calculation_version":"1.0.1"}'

{
  "inputs": {
    "mode": "arithmetic",
    "a": 2,
    "d": 3,
    "n": 5
  },
  "calculation_version": "1.0.1"
}

POST /api/v1/calc/sequence. This is a POST calculate endpoint — do not GET it.

Full REST contract: REST API docs.

Tool id: sequence
Engine: sequence
REST: POST /api/v1/calc/sequence
MCP: execute_calculation with capability_id: "math.sequences"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.0.1)
Versioned output schema: Immutable pin (1.0.1)

References

Human-readable sources plus CVP reference evidence classes.

Sources

ISO 80000-2:2019 Quantities and units — Mathematics
Knuth, The Art of Computer Programming, Fibonacci F₀=0 F₁=1 and linear recurrences

Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior

Try with an agent

Inspect, then execute. Same engine as REST and the human calculator.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"math.sequences"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: execute_calculation' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"execute_calculation","arguments":{"capability_id":"math.sequences","inputs":{"mode":"arithmetic","a":2,"d":3,"n":5},"calculation_version":"1.0.1"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

Pin calculation_version (1.0.1) when the result must stay reproducible.

Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.