StackOptic
Back to Search
t5k.org favicon

t5k.org

https://t5k.org· First analyzed 10 May 2026· Updated 10 May 2026
Export
t5k.org
Desktop screenshot of t5k.org
Mobile screenshot of t5k.org
Mobile

Sponsored

Hosting Provider

DigitalOcean
digitalocean.com

IP Address

45.55.123.225

Site Location

🇺🇸 United Statesvia ip

Server Location

🇺🇸 Clifton, United States

ASN

AS14061

Organization

Digital Ocean

Server

Apache

Nameservers

ns-cloud-d4.googledomains.com.ns-cloud-d1.googledomains.com.ns-cloud-d2.googledomains.com.ns-cloud-d3.googledomains.com.

Performance

75

Core Web Vitals

Weight

First Contentful Paint
3.1 s10%
Speed Index
4.0 s10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
277 KB
11 requests
0–49
50–89
90–100

Architecture Stack

Monolithic
⚙️ SSR
Frontend
Styling
Tailwind CSS
Infrastructure
Hosting
DigitalOcean

Technology Stack

6 Technologies Detected

CSS Frameworks

2
Bootstrapv4.3.1
Tailwind CSS

Libraries

1
jQueryv3.3.1

Icon Libraries

1
Font Awesome

Fonts

1
Google Fonts

Web Servers

1
Apachev2.4.52

SEO Analysis

C64/100
18
8
0
Meta Tags13/15
Content10/12
Headings5/8
Technical13/25
E-E-A-T3/7
Images4/7
Links4/5
URL5/5
Social0/5
Freshness0/4
Mobile4/4
Indexability3/3
T
t5k.orgt5k.org

PrimePages: prime number research records and results

Access to hundreds of pages of award-winning information on prime numbers--with links to thousands of pages elsewhere. We host the searchable database of the...

Description truncated.
Title Length53 chars

Recommended: 50-60 chars (~328px / 580px)

Description Length302 chars

Recommended: 120-160 chars

Issues (0)

    8 issues found

    Upgrade to view details

    Crawlability

    Sitemap
    robots.txt

    24 rules

    Allows all crawlers

    Local SEO

    Local Search Readiness

    6/100
    Poor
    2 13 2

    This site doesn't appear to be a local business. Local SEO signals are optional for non-local websites.

    Sponsored

    AI & LLM Readiness

    D43/100
    Bot Access
    20/25
    Machine Read.
    12/25
    Schema Data
    0/25
    Citation
    11/25

    AI Bot Access

    14/14 accessible
    AI Search
    OAI-SearchBot
    PerplexityBot
    Claude-SearchBot
    Gemini-Deep-Research
    DuckAssistBot
    Training
    GPTBot
    ClaudeBot
    Google-Extended
    Meta-ExternalAgent
    Bytespiderinfo
    Amazonbot
    Applebot-Extended
    CCBotinfo
    Fetch
    ChatGPT-User

    Machine Readability

    llms.txt
    llms-full.txt
    Semantic HTML
    Heading Hierarchy
    navheader/footer
    Text ratio:15%
    Words:489
    Token eff.:Optimal
    Sections/1K:6.1
    Depth:2/5

    Structured Data

    No Schema

    Citation Readiness

    Opening Summary73w
    Descriptive Headingsavg 1.3w
    Canonical URL
    Open Graph0/3
    Twitter Card0/3
    Language Tag
    Publish Date
    Author Info
    Lists
    Tables
    TL;DR / Summary
    About Page Link
    Recommendations (8)
    AI readiness recommendation preview...
    Upgrade to view recommendations

    Sponsored

    Accessibility

    WCAG 2.1 Compliance

    Evaluates how accessible your website is for users with disabilities, based on WCAG 2.1 guidelines. Checks images, forms, keyboard navigation, ARIA roles, and color contrast.
    A
    85/100
    13
    Passed
    2
    Critical
    0
    Warnings
    Images & Alt Text
    20/20
    Checks if images have descriptive alt text for screen readers and visually impaired users.
    Semantic Structure
    17/20
    Evaluates proper use of HTML5 semantic elements (header, nav, main, footer) and heading hierarchy.
    Forms & Inputs
    15/15
    Verifies form fields have labels, error messages are clear, and inputs are properly associated.
    Color & Contrast
    15/15
    Tests text-to-background color contrast ratios against WCAG AA/AAA minimum requirements.
    Keyboard & Focus
    9/15
    Ensures all interactive elements are reachable and operable via keyboard (tab, enter, escape).
    ARIA & Roles
    9/15
    Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.
    1 recommendation
    • •Accessibility recommendation preview...
    Upgrade to view recommendations

    Carbon Footprint

    SWDM v4 · Eco-Score

    Carbon emissions estimated using the Sustainable Web Design Model v4 (SWDM v4). Factors in data center, network, and device energy across new and returning visitors. Grade thresholds based on HTTP Archive percentiles.
    75/100
    A+
    28 mg
    CO₂e / view
    277.3 KB
    Page Weight
    90%
    Cleaner Than
    New Visitor
    32 mg
    vs
    Returning (cached)
    16 mg
    Annual (10K/mo)
    3.4 kg
    Emission Segments
    Data Center
    1 mg
    Network
    8 mg
    Device
    18 mg
    Resource Breakdown
    JavaScript
    54.7 KB
    Images
    160.5 KB
    CSS
    54.3 KB
    Fonts
    2.0 KB
    HTML
    5.8 KB
    Green Hosting Verified
    DigitalOcean
    Provider Match
    2 recommendations
    • •Carbon footprint recommendation preview...
    Upgrade to view recommendations
    F

    Security Score

    21%Critical
    Interactive

    HTTPS

    No WAF

    57d

    Certificate Details

    Type

    Domain Validated (DV)

    Certificate Authority

    Let's Encrypt

    Key Algorithm

    RSA (2048 bit)

    Signature

    SHA-256 with RSA

    TLS Version

    TLSv1.3

    HTTP Protocol

    HTTP/1.1

    Valid From

    08.04.2026

    Valid Until

    07.07.2026

    Subject Alternative Names (2)

    primes.utm.edut5k.org

    SHA-256 Fingerprint

    6F:61:F6:A4:E5:21:78:DB:33:5B:F6:5A:19:25:09:C0:FC:82:0E:00...

    Top Recommendations

    Security recommendation preview

    Upgrade to view recommendations
    Upgrade to view header details

    HTTP Headers

    Developer Console

    accept-ranges
    bytes
    connection
    Keep-Alive
    content-encoding
    📦 Gzip(gzip)
    content-length
    5654
    content-type
    text/html
    date
    Sun, 10 May 2026 19:38:58 GMT
    Good Warning Issue

    Email Infrastructure

    Google Workspace

    Score

    70

    SPF
    DKIM
    DMARC

    MX Records (5)

    alt4.aspmx.l.google.com
    aspmx.l.google.com
    alt1.aspmx.l.google.com
    alt3.aspmx.l.google.com

    +1 more

    Domain Information

    t5k.org

    Domain Age
    3y 4m

    Created

    15.12.2022

    Expires

    15.12.2026

    Last Updated

    05.12.2025

    Registrar

    Squarespace Domains II LLC

    DNSSEC
    Not Enabled

    Privacy & Compliance

    Cookie Consent Banner
    Privacy Policy
    Terms of Service

    GDPR Indicators

    Privacy policy page linked

    Mobile Compatibility

    Viewport & Responsive Test

    Tests how well your website works on mobile devices. Checks viewport configuration, responsive layout, touch targets, font readability, and simulates rendering across different screen sizes.
    C
    65/100
    Mobile Friendly1 breakpoint
    Viewport Meta
    The viewport meta tag tells mobile browsers how to scale the page. Without it, mobile devices render at desktop width.
    Responsive Design
    Uses CSS media queries or flexible layouts to adapt content to different screen sizes automatically.
    Touch Icons
    Apple touch icons and favicons displayed when users add the site to their home screen on mobile devices.
    Readable Font Size
    Base font size should be at least 16px on mobile to ensure text is readable without zooming.
    Relative Units
    Using em, rem, %, or vw instead of fixed px values allows content to scale properly across screen sizes.
    No H-Scroll Risk
    No elements wider than the viewport that would cause horizontal scrolling on mobile devices.
    Tap Targets OK
    Interactive elements (buttons, links) are at least 48x48px with enough spacing to prevent accidental taps.
    No Fixed Widths
    No elements with fixed pixel widths that could overflow on smaller screens and break the layout.
    Viewport
    width=device-width, initial-scale=1, shrink-to-fit=no
    2 recommendations
    • •Mobile compatibility recommendation preview...
    Upgrade to view recommendations

    Typography & Readability

    Roboto

    WCAG Partial
    66/100
    Readability
    /30
    21/30

    14px · LH 1.50

    Hierarchy
    /20
    10/20

    2.78x ratio

    WCAG
    /25
    17/25

    1:1 min contrast

    Performance
    /25
    18/25

    1 font · 1 req

    Heading Font

    Roboto

    Sans40px

    Body Font

    Roboto

    Sans14px

    Contrast Ratio

    1:1

    33 issues

    Reading Comfort

    ~36 CPL

    Narrow lines
    40px
    h1
    28px
    h3
    14px
    p

    ⚠️ Small text: 14px may strain on mobile. Use ≥16px for WCAG compliance.

    ✅ Optimal line spacing: 1.50 ratio (ideal range 1.4–1.6).

    ⚠️ Partial contrast: 33 elements below WCAG AA threshold (min 1.0:1).

    ❌ Broken heading hierarchy: 2 level skip(s). Screen readers rely on sequential headings (h1→h2→h3).

    ✅ Strong hierarchy: Headlines are 2.8x larger than body text.

    ✅ Lean font stack: 1 font families keeps load times fast.

    GGoogle FontsFlesch 64

    Color Palette

    9 unique colors
    4.62:1 AA Light
    #ffffff
    Background· 24.5%
    #6f7583
    Secondary· 5.2%
    #e8f6e9
    Primary· 29.499999999999996%
    #cee3f1
    Accent· 9.3%
    #2b378c
    Accent· 7.8%
    #76b1e1
    Accent· 7.3%
    #c8d1d6
    Secondary· 6.6%
    #82c8c1
    Secondary· 5.1%

    Business & Marketing Stack

    1 Tools Detected

    Growing

    Behavior Analytics

    1
    Google AnalyticsFree

    User behavior and product analytics

    1

    Categories

    1

    Total Tools

    0

    Enterprise

    0

    Mid-Market

    Assessment: Growing marketing technology adoption

    Sponsored

    Scripts & Styles

    7 Resources

    3
    Scripts
    4
    Styles
    0
    Async
    0
    Defer

    Top Script Sources

    ajax.googleapis.com(1)cdnjs.cloudflare.com(1)maxcdn.bootstrapcdn.com(1)

    Website Identity

    t5k.org

    3 years old
    Location detected: 🇺🇸 United Statesvia ip
    Squarespace Domains II LLC📧 Google Workspaceen

    Sponsored

    Last analyzed: 10 May 2026 at 19:39

    Historical Analysis & Change Tracking