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出典:Wiktionary
pyramidal number (複数形 pyramidal numbers)
出典:Wikipedia
出典:『Wikipedia』 (2010/03/01 17:38 UTC 版)
A pyramidal number is a figurate number that represents a pyramid with a base and a given number of sides. The term is most often used to refer to square pyramidal numbers, which have four sides, but it can also refer to:
Pyramidal number