276

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Number

$276$ (two hundred and seventy-six) is:

$2^2 \times 3 \times 23$

The $1$st positive integer which begins an aliquot sequence whose final status is unknown.

The $12$th hexagonal number after $1$, $6$, $15$, $28$, $45$, $66$, $91$, $120$, $153$, $190$, $231$:

$\ds 276 = \sum_{k \mathop = 1}^{12} \paren {4 k - 3} = 12 \left({2 \times 12 - 1}\right)$

The $14$th inconsummate number after $62$, $63$, $65$, $75$, $84$, $95$, $161$, $173$, $195$, $216$, $261$, $266$, $272$:

$\nexists n \in \Z_{>0}: n = 276 \times \map {s_{10} } n$

The $19$th untouchable number after $2$, $5$, $52$, $88$, $96$, $120$, $124$, $146$, $162$, $188$, $206$, $210$, $216$, $238$, $246$, $248$, $262$, $268$

The $23$rd triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $136$, $153$, $171$, $190$, $210$, $231$, $253$:

$\ds 276 = \sum_{k \mathop = 1}^{23} k = \dfrac {23 \times \paren {23 + 1} } 2$

Also see

• Aliquot Sequence starting from $276$

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• Previous  ... Next: Untouchable Number
• Previous  ... Next: Inconsummate Number

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $276$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $276$