pentagonalnumberseries
nounUK /pɛnˈtæɡənəl ˈnʌmbə ˈsɪəriːz/
US /pɛnˈtæɡənəl ˈnʌmbər ˈsɪriz/
A list of numbers made by adding dots in bigger and bigger pentagon shapes.
The pentagonal number series starts 1, 5, 12, 22, and 35.
OTHER MEANINGS
2. The sequence whose nth term equals n(3n−1)/2, giving 1, 5, 12, 22, 35, and so on.
The formula for the pentagonal number series is n(3n−1)/2.
3. A series of numbers that can be drawn as nested pentagons of dots.
She drew the pentagonal number series on paper to see the pattern.
4. A mathematical pattern used in number theory and combinatorics.
The pentagonal number series appears in Euler's pentagonal number theorem.