308

Number
$308$ (three hundred and eight) is:


 * $2^2 \times 7 \times 11$


 * The $7$th heptagonal pyramidal number after $1$, $8$, $26$, $60$, $115$, $196$:
 * $308 = 1 + 7 + 18 + 34 + 55 + 81 + 112 = \dfrac {7 \left({7 + 1}\right) \left({5 \times 7 + 2}\right)} 6$


 * The $51$st nontotient:
 * $\nexists m \in \Z_{>0}: \phi \left({m}\right) = 308$
 * where $\phi \left({m}\right)$ denotes the Euler $\phi$ function