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Jul
20
comment What is the upper bound on $T(n) = 3T(n/2) + n$?
The sum starts at $k=1$, so the result is correct.
Jul
2
awarded  Curious
Jun
15
comment What is the probability that all 4 cards have different value?
IMO the approach and the result are correct.
May
31
answered How many $3$-Letter Strings from come from $ABRACADABRA$?
May
31
comment How many $3$-Letter Strings from come from $ABRACADABRA$?
I've got only 97 strings ...
May
6
comment fixed point iteration $x_{k+1}=f(x_k)$ with multiple fixed points
Why is $f(0)=0$?
May
4
asked Practical use and applications of improper integrals
Apr
27
awarded  Custodian
Apr
27
reviewed Approve suggested edit on Good book on integral calculus (improper integrals, integrals with parameters, special functions)
Apr
27
asked Good book on integral calculus (improper integrals, integrals with parameters, special functions)
Apr
11
revised Book on combinatorial identities
corrected spelling
Apr
10
comment Prove or disprove: $(\frac{1}{n})^n(1 - \frac{1}{n})^{n^2-n} \simeq \frac{1}{n!}$ as $n \rightarrow \infty$.
What does the Stirling formula tells you, if you replace $1/e$ by $(1-1/n)^n$?
Apr
10
comment Book on combinatorial identities
The book of Riordan is OK. I would have hope for more examples with direct combinatorial arguments, yet the methods presented are interesting and worth studying.
Apr
10
comment Limit of a function without using L'Hôpital Rule
I agree with Daniel Fischer. Your question is clearly dependent on how you define the logarithm (hence, what properties of the logarithm are assumed). That is because your question is a basic property of the logarithm (which, in terms of derivatives, is the derivative of $\log(1+x)$ at $x=0$.
Apr
10
answered Implicit solution to second-order non-linear differential equation
Apr
8
comment Book on combinatorial identities
From what I've seen, these only list combinatorial identities. There are no (combinatorial) proofs.
Apr
7
revised Making 7 vertices triangle free graph bipartite by deleting an edge
added 205 characters in body
Apr
7
revised Making 7 vertices triangle free graph bipartite by deleting an edge
added 410 characters in body
Apr
7
revised Making 7 vertices triangle free graph bipartite by deleting an edge
added 278 characters in body
Apr
7
answered Making 7 vertices triangle free graph bipartite by deleting an edge