14-09-09 Sum of a series...

Find the value of
[\frac{n+1}{2}]+[\frac{n+2}{2^2}]+[\frac{n+4}{2^3}]+...+[\frac{n+2^k}{2^{k+1}}]+... sum goes to infinity...

Edit: [.] is the greatest integer Function

We have done something of this kind before..

11 Answers

1
Arshad ~Died~ ·

sir dont u think that the third term should have 2^3 in the denominator.......

1
aieeee ·

if we write the kth term as : (n + 2k) / 2k+1

so,we can write its summation to get the answer : \sum_{k=0}^{infinity}{n / 2^k^+^1} + \sum_{k=0}^{infinity}{2^k / 2^k^+^1}

i think its rite unless i hv made som blunder

3
msp ·

Sandwich theorem will give us two inequalities but we can get our ans only if it gives us a tight inequality.

3
msp ·

also abhi u cant assume the nth term like as we dont know whether it is an integer,bcos at some term 'r' we have denominator gr8er than numerator so the rest term of the sequence will be zero.

1
Grandmaster ·

who is this!!!!

62
Lokesh Verma ·

@everyone.. [.] is the greatest integer function..

62
Lokesh Verma ·

how?

106
Asish Mahapatra ·

incomplete

ans: n

1
arpan sinha ·

the general term is \sum_{0}^{inf }{(n+2^k)/2^(k+1)
=\sum_{0}^{inf }{[(n/2^(k+1))+1/2]
The first term will continue to be an integer until 2^(k+1)>n
or, k> log2 n - 1
so the rest of the terms r 0 since [.] is GIF.
this the conclusion i cud reach so far!!!
trying to work out more steps...
tell me if my approach is crrt!!!!

62
Lokesh Verma ·

Find: f(x+p) - f(x) for some integer p

1
Philip Calvert ·

S=\sum_{k=0}^{\inf}{\left[ \frac{n+2^{k}}{2^{k+1}}\right]} \\\texttt{From Hermites identity :} \\\left[ x\right]+\left[x+\frac{1}{2} \right]=[2x] \\S=\sum_{k=0}^{\inf}{\left[\frac{n}{2^k}\right]-\left[\frac{n}{2^{k+1}} \right]} \\\texttt{which telescopes to give :} \\{S=[n]}

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