Heptagonal number
= Heptagonal number
{wiki=Heptagonal_number}
A heptagonal number is a figurate number that represents a heptagon (a seven-sided polygon). The formula for the \\(n\\)-th heptagonal number \\(H_n\\) is given by: \\\[ H_n = \\frac\{n(5n - 3)\}\{2\} \\\] where \\(n\\) is a positive integer.