Centered triangular number

Rarity: Common

The most frequent rarity: most Wikipedia articles become Commons.

Rarity follows how well known the article is: its views on the French and English Wikipedia over a year, and the number of languages it exists in.

At a glance

Class

Notion

Domain

Science and technology

In collections

Nobody has pulled it yet.

What Wikipedia says

A centered (or centred) triangular number is a centered figurate number that represents an equilateral triangle with a dot in the center and all its other dots surrounding the center in successive equilateral triangular layers.

Excerpt from the Wikipedia article “Centered triangular number”, under the CC BY-SA 4.0 license. Read the article on Wikipedia

Image: Stefan Friedrich Birkner, CC BY-SA 3.0, via Wikimedia Commons.