# 7626

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## Number

$7626$ (seven thousand, six hundred and twenty-six) is:

$2 \times 3 \times 31 \times 41$

The $62$nd hexagonal number after $1$, $6$, $15$, $28$, $45$, $66$, $91$, $\ldots$, $5565$, $5778$, $5995$, $6216$, $6441$, $6670$, $6903$, $7140$, $7381$:
$7626 = \ds \sum_{k \mathop = 1}^{62} \paren {4 k - 3} = 62 \paren {2 \times 62 - 1}$

The $123$rd triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $6786$, $6903$, $7021$, $7140$, $7260$, $7381$, $7503$:
$7626 = \ds \sum_{k \mathop = 1}^{123} k = \dfrac {123 \times \paren {123 + 1} } 2$