481

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Number

$481$ (four hundred and eighty-one) is:

$13 \times 37$

The smallest positive integer whose square is the sum of $3$ fourth powers:

$481^2 = 12^4 + 15^4 + 20^4$

The $13$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $96$, $133$, $176$, $225$, $280$, $341$, $408$:

$\ds 481 = \sum_{k \mathop = 1}^{13} \paren {6 k - 5} = 13 \paren {3 \times 13 - 2}$

Also see

• Smallest Square which is Sum of 3 Fourth Powers

• Previous  ... Next: Octagonal Number

Sources

• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $481$