Help in easy floor summation

How do I calculate the following summation? \[ \sum_{i = 1}^{\lfloor \sqrt{n} \rfloor} \Bigl \lfloor \frac{n}{i^2} \Bigr \rfloor i^2 \] \[ \sum_{i = 1}^{\lfloor \sqrt[3]{n} \rfloor} \Bigl \lfloor \frac{n}{i^3} \Bigr \rfloor i^3 \]

and generalize for any power?

#NumberTheory

Note by Sahil Singh
1 year, 2 months ago

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Comments

Ni2=1 \left\lfloor\frac{N}{i^2}\right\rfloor=1 whenever 1Ni2<2 1\leq\frac{N}{i^2}<2 The sum can be reduced like this even further. S=1n2ni2i2+i=n2n1.i2 S= \sum_{1}^{\bigl \lfloor \sqrt{\frac{n}{2}} \bigr \rfloor} \Bigl \lfloor \frac{n}{i^2} \Bigr \rfloor i^2 + \sum_{i = \bigl \lfloor \sqrt{\frac{n}{2}} \bigr \rfloor}^{\lfloor \sqrt{n} \rfloor} 1 . i^2 @Calvin Lin @Agnishom Chattopadhyay Maybe you guys can help further.

Rishabh Deep Singh - 1 year, 2 months ago

This is from a live Code Chef problem.

Calvin Lin Staff - 1 year, 2 months ago

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it is over now we can discuss it.

Rishabh Deep Singh - 1 year, 2 months ago
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