Ask Me Help Desk - What would be the next number in this series -3 6 -18 72 -360.

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What would be the next number in this series -3 6 -18 72 -360.

What would be the next number in this series? -3 6 -18 72 -360

Successive multiplication is done using consecutive natural numbers, and then alternating signs.

$a_{n}=3\cdot (-1)^{n}\cdot n!=3n!\cdot cos(n{\pi})$

Let n=6 to find the next number.

You're welcome.

Yes, I am sure you knew it but did not notice. On my Voyage 200, if I

type in $(-1)^{n}$ , it gives

$cos({\pi}n)+i\cdot sin({\pi}n)$ .

Which, as you probably know, is the Euler formula

$e^{n\cdot {\pi}\cdot i}$

Therefore, $(-1)^{n}=e^{n{\pi}i}$

It would appear we like this post more than the OP, for they never returned.:rolleyes:

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