Integer Recurrence Explorer (PWA)

Live app: https://ncg777.github.io/integer-recurrence-explorer/

Explore classic and algorithmic integer sequences interactively. Pick a recurrence, set initial conditions and parameters, choose output length and range handling, then copy or download the generated terms.

This project is a lightweight Angular single-page app configured for GitHub Pages hosting and installable as a basic PWA.

Features

• Built‑in catalog of sequences
  • Classic: Fibonacci, Lucas, Tribonacci, Pell, Padovan, Perrin, Collatz
  • 32‑bit generators with parameters:
    • Xorshift (shifts A,B,C)
    • LCG32 (a, c)
    • Weyl32 (omega)
    • LFSR32 (polynomial)
    • SplitMix32
    • ROL‑Mix (rotate amount)
• Initial conditions editor; quick “Fill default initial” helper
• Output length control
• Range handling (Max value):
  • mod: wrap modulo N
  • bounce: reflect in [0, N-1] (sawtooth bounce)
• One‑click Copy to Clipboard or Download .txt
• Installable via web app manifest (basic PWA)
• Live details panel: shows formula, notes, and typical initials for the selected recurrence

Try it online

Open the app here: https://ncg777.github.io/integer-recurrence-explorer/

How it works

• Recurrence model
  • Recurrence { name, order, next(values: number[], index?: number): number }
  • LambdaRecurrence provides a simple wrapper around a rule function
  • order controls how many prior terms feed the next value (order 0 means index‑driven)
• Generation pipeline
  • Service (RecurrenceService) takes a recurrence, initial conditions, length, and range mode
  • Initials are normalized to exactly order terms: too short → left‑pad with zeros; too long → first N
  • Each step calls recurrence.next(window, index) and then applies range handling (mod or bounce)
  • Results stream via an RxJS BehaviorSubject for UI components
• UI components
  • RecurrenceInputComponent: choose recurrence, tweak parameters, enter initials, length, and range
  • RecurrenceDetailsComponent: synchronized, educative description and formula for the selected recurrence
  • SequenceViewerComponent: shows the sequence, copy/download actions

Usage notes

• Initial conditions
  • For order‑2 sequences (e.g., Fibonacci), provide two initials like 0 1
  • For order‑3 sequences (e.g., Tribonacci/Padovan/Perrin), provide three initials
• Parameters (when applicable)
  • Xorshift: shift counts A, B, C
  • LCG32: multiplier a, addend c (32‑bit arithmetic)
  • Weyl32: step omega (decimal or hex like 0x9E3779B9)
  • LFSR32: feedback polynomial (hex)
  • ROL‑Mix: left rotation amount
• Range handling
  • mod: value mod N in [0, N-1]
  • bounce: reflects values into [0, N-1] using a period of 2*(N-1)

Development

Prerequisites

• Node.js 18+ and npm

Install dependencies

npm install

Run unit tests (Jest)

npm test

Serve locally (Angular CLI)

npx ng serve --open

Build for production (outputs to docs/ for GitHub Pages)

npx ng build --configuration production

Notes

• Production build sets baseHref and deployUrl to /integer-recurrence-explorer/ (see angular.json).
• The PWA manifest is at src/assets/manifest.webmanifest and is linked from src/index.html.

Deploying to GitHub Pages

This repo is configured to publish the static site from the docs/ folder on the default branch.

Typical flow:

1. Build the site: npx ng build --configuration production
2. Commit the updated docs/ artifacts
3. Push to the repository’s default branch
4. Ensure repository Settings → Pages → Source is set to “Deploy from a branch” with folder /docs

The live URL is: https://ncg777.github.io/integer-recurrence-explorer/

PWA details

• Manifest (src/assets/manifest.webmanifest)
  • name: “Integer Recurrence Explorer”
  • start_url: /integer-recurrence-explorer
  • display: standalone
  • theme/background colors
  • icon: assets/favicon.png (1024×1024)
• Service worker
  • This app does not currently register a service worker; offline behavior depends on normal browser caching
  • It is still installable thanks to the manifest

Project structure (high level)

• src/app/models/recurrence.ts — Recurrence interfaces and LambdaRecurrence
• src/app/services/recurrence-factory.ts — Built‑in recurrence catalog and helpers
• src/app/services/recurrence.service.ts — Sequence generation and range handling
• src/app/components/* — UI components for input and display
• src/assets/manifest.webmanifest — PWA manifest
• angular.json — Build/serve configuration (production builds to docs/ with GitHub Pages paths)

Known limitations

• Integer range and overflow
  • Several generators use 32‑bit operations; results may wrap and become negative due to signed 32‑bit math in JavaScript
• Very long sequences can be memory‑intensive in the browser
• Collatz expects positive integers; non‑positive/invalid inputs are guarded in code to avoid degenerate behavior
• No service worker; offline use is limited

License

See the LICENSE file in this repository for license details.