412

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Number

$412$ (four hundred and twelve) is:

$2^2 \times 103$

The $4$th positive integer $n$ after $157$, $262$, $367$ for which $\map \phi {2 n + 1} < \map \phi {2 n}$:

$\map \phi {2 \times 412 + 1} = 400$, $\map \phi {2 \times 412} = 408$

The $42$nd noncototient after $10$, $26$, $34$, $50$, $\ldots$, $344$, $346$, $362$, $366$, $372$, $386$, $394$, $404$:

$\nexists m \in \Z_{>0}: m - \map \phi m = 412$

where $\map \phi m$ denotes the Euler $\phi$ function

Also see

• Previous  ... Next: Numbers for which Euler Phi Function of 2n + 1 is less than that of 2n
• Previous  ... Next: Noncototient

Sources

• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $157$