1855

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Number

$1855$ (one thousand, eight hundred and fifty-five) is:

$3 \times 5 \times 53$

The $35$th second pentagonal number after $2$, $7$, $15$, $26$, $\ldots$, $1107$, $1190$, $1276$, $1365$, $1457$, $1552$, $1650$, $1751$:

$1855 = \dfrac {35 \paren {3 \times 35 + 1} } 2$

The $70$th generalized pentagonal number after $1$, $2$, $5$, $7$, $12$, $15$, $\ldots$, $1335$, $1365$, $1426$, $1457$, $1520$, $1552$, $1617$, $1650$, $1717$, $1751$, $1820$:

$1855 = \dfrac {35 \paren {3 \times 35 + 1}} 2$

Also see

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