TRIANGULAR NUMBERS


Meaning of TRIANGULAR NUMBERS in English

noun plural

: 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

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.