triangular numbers

plural noun

: the successive sums n(n + 1)/2 where n = 1, 2, 3, … of the first n natural numbers 1, 3, 6, 10, 15, … representable by dots arranged in triangles

Word History

First Known Use

1795, in the meaning defined above

Time Traveler
The first known use of triangular numbers was in 1795

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Cite this Entry

“Triangular numbers.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/triangular%20numbers. Accessed 14 Apr. 2024.

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