Triangular number (English Wikipedia)

Beldon, Tom; Gardiner, Tony (2002). "Triangular Numbers and Perfect Squares". The Mathematical Gazette. 86 (507): 423–431. doi:10.2307/3621134. JSTOR 3621134. Retrieved 25 April 2024.

mathcircles.org (Global: low place; English: low place)

"The Handshake Problem | National Association of Math Circles". MathCircles.org. Archived from the original on 10 March 2016. Retrieved 12 January 2022.

mathsisfun.com (Global: low place; English: low place)

"Triangular Number Sequence". Math Is Fun.

semanticscholar.org (Global: 15^th place; English: 8^th place)

api.semanticscholar.org

Baumann, Michael Heinrich (2018-12-12). "Die $k$ -dimensionale Champagnerpyramide" (PDF). Mathematische Semesterberichte (in German). 66: 89–100. doi:10.1007/s00591-018-00236-x. ISSN 1432-1815. S2CID 125426184.
Liu, Zhi-Guo (2003-12-01). "An Identity of Ramanujan and the Representation of Integers as Sums of Triangular Numbers". The Ramanujan Journal. 7 (4): 407–434. doi:10.1023/B:RAMA.0000012425.42327.ae. ISSN 1382-4090. S2CID 122221070.
Engelstein, Geoffrey; Shalev, Isaac (2019-06-25). Building Blocks of Tabletop Game Design. doi:10.1201/9780429430701. ISBN 978-0-429-43070-1. S2CID 198342061.
Stone, John David (2018), Algorithms for Functional Programming, Springer, p. 282, doi:10.1007/978-3-662-57970-1, ISBN 978-3-662-57968-8, S2CID 53079729

stir.ac.uk (Global: low place; English: 9,999^th place)

dspace.stir.ac.uk

Ross, H.E.; Knott, B.I. (2019). "Dicuil (9th century) on triangular and square numbers". British Journal for the History of Mathematics. 34 (2): 79–94. doi:10.1080/26375451.2019.1598687. hdl:1893/29437.

uni-bayreuth.de (Global: low place; English: low place)

epub.uni-bayreuth.de

Baumann, Michael Heinrich (2018-12-12). "Die $k$ -dimensionale Champagnerpyramide" (PDF). Mathematische Semesterberichte (in German). 66: 89–100. doi:10.1007/s00591-018-00236-x. ISSN 1432-1815. S2CID 125426184.

uregina.ca (Global: 9,054^th place; English: 5,053^rd place)

mathcentral.uregina.ca

Eves, Howard. "Webpage cites AN INTRODUCTION TO THE HISTORY OF MATHEMATICS". Mathcentral. Retrieved 28 March 2015.

web.archive.org (Global: 1^st place; English: 1^st place)

Hayes, Brian. "Gauss's Day of Reckoning". American Scientist. Computing Science. Archived from the original on 2015-04-02. Retrieved 2014-04-16.
"The Handshake Problem | National Association of Math Circles". MathCircles.org. Archived from the original on 10 March 2016. Retrieved 12 January 2022.

wolfram.com (Global: 1,091^st place; English: 1,169^th place)

mathworld.wolfram.com

Eric W. Weisstein. "Triangular Number". Wolfram MathWorld. Retrieved 2024-04-14. See equations 18–20.

demonstrations.wolfram.com

"Wolfram Demonstrations Project". demonstrations.wolfram.com. Retrieved 2026-07-23.

worldcat.org (Global: 4^th place; English: 4^th place)

search.worldcat.org

Baumann, Michael Heinrich (2018-12-12). "Die $k$ -dimensionale Champagnerpyramide" (PDF). Mathematische Semesterberichte (in German). 66: 89–100. doi:10.1007/s00591-018-00236-x. ISSN 1432-1815. S2CID 125426184.
Liu, Zhi-Guo (2003-12-01). "An Identity of Ramanujan and the Representation of Integers as Sums of Triangular Numbers". The Ramanujan Journal. 7 (4): 407–434. doi:10.1023/B:RAMA.0000012425.42327.ae. ISSN 1382-4090. S2CID 122221070.

Triangular number (English Wikipedia)

americanscientist.org (Global: 9,393rd place; English: 7,744th place)

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mathcircles.org (Global: low place; English: low place)

mathsisfun.com (Global: low place; English: low place)

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stir.ac.uk (Global: low place; English: 9,999th place)

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wolfram.com (Global: 1,091st place; English: 1,169th place)

mathworld.wolfram.com

demonstrations.wolfram.com

worldcat.org (Global: 4th place; English: 4th place)

search.worldcat.org

americanscientist.org (Global: 9,393^rd place; English: 7,744^th place)

archive.org (Global: 6^th place; English: 6^th place)

arxiv.org (Global: 49^th place; English: 31^st place)

books.google.com (Global: 3^rd place; English: 3^rd place)

doi.org (Global: 2^nd place; English: 2^nd place)

hdl.handle.net (Global: 66^th place; English: 34^th place)

jstor.org (Global: 23^rd place; English: 15^th place)

semanticscholar.org (Global: 15^th place; English: 8^th place)

stir.ac.uk (Global: low place; English: 9,999^th place)

uregina.ca (Global: 9,054^th place; English: 5,053^rd place)

web.archive.org (Global: 1^st place; English: 1^st place)

wolfram.com (Global: 1,091^st place; English: 1,169^th place)

worldcat.org (Global: 4^th place; English: 4^th place)