Number sphenic

A number sphenic is a strictly positive whole which is the product of three distinct factors first. The Fonction of Möbius turns over -1 when one enters a number sphenic.

The definition requires that each of the three factors first be expressed only once; for example $60\; =\; 2^2\; \backslash \; times\; 3\; \backslash \; times\; 5\; \backslash ,$ has 3 factors well first, but is not sphenic because factor 2 is there twice.

All the numbers sphenic have eight dividers exactly. If we express a number sphenic in the form $n\; =\; p\; \backslash \; times\; Q\; \backslash \; times\; r$, then the whole of its dividers is:

$\backslash \; left\; \backslash \; \{1,\; \backslash \; p,\; \backslash \; Q,\; \backslash \; R,\; \backslash \; p\; Q,\; \backslash \; p\; R,\; \backslash \; Q\; R,\; \backslash \; N\; \backslash \; right\; \backslash \}$.

The few first numbers sphenic are: 30, 42, 66, 70, 78, 102, 105, 110, 114, 130, 138, 154, 165, 170, 174, 182, 186, 190,…, 230, 231,…

External bonds

• Numbers sphenic on the electronic Encyclopedia of the whole continuations.

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