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 Dec31 awarded Yearling Dec31 awarded Yearling Sep26 answered Combinatorics: relations and cardinality. Sep3 answered Relation between articulation points and bridge edges Jun25 comment Maximum n so there exist two equal sum, 3-element subsets from a 9 element set of positive integers This paper gives a $9$ element set with all distinct subset sums (not just subsets of size $3$), with largest number being $161$. So this reduces upper bound here to $161$. And there are $84$ subsets of size $3$ in a $9$ element set. So the lower bound above is in fact $29$. Jun15 comment devising a code for five symbols en.wikipedia.org/wiki/Huffman_coding Jun15 comment Find Total number of ways out of N Number taking K numbers every M interval math.stackexchange.com/questions/405305/combination-problem Jun14 awarded Revival Jun14 comment Closed form for $\sum_{n=1}^\infty\frac{\psi(n+\frac{5}{4})}{(1+2n)(1+4n)^2}$ Can you please refer to some place which elaborates a bit more on this? Jun14 answered Orthogonality of eigenvectors of laplacian Jun14 comment $\displaystyle f\colon [a,b] \rightarrow \mathbb R$ is a strictly monotone continuous function @ronno I have moved my comment to an answer, but I am having some trouble posting to the chat room. Maybe you can upvote this yourself and get this question removed from unanswered. Jun14 answered $\displaystyle f\colon [a,b] \rightarrow \mathbb R$ is a strictly monotone continuous function May29 comment Bounding the size of a set that is a little better than a dominating set Is there a power $\delta$ missing at the end of $E[|Z|]$ expression? Looks like it should be $ne^{-p}(p+e^{-p(\delta + 1)})^{\delta}$. May27 comment Uniquely $3$-edge-colourable $3$-regular graph with $\chi'(G) = 3$ has exactly $3$ Hamiltonian cycles? Number of vertices must be even here, as each degree is odd and degree sum must be even. May27 answered Uniquely $3$-edge-colourable $3$-regular graph with $\chi'(G) = 3$ has exactly $3$ Hamiltonian cycles? May24 comment Need help to prove Looks like you need $\prod_{i=1}^k \frac{a_i}{1+a_i}$ to converge to zero as $k \rightarrow \infty$. May24 comment Distribution of Digit Products @Lucas Yes, that argument is not enough by itself. Do you have any upper bound for number of $x < N$ resulting in $0$, for a given $N$? May24 comment Distribution of Digit Products Even numbers must be infinitely more often than odd, as even if a single digit in $x$ is even, $P^\infty (x)$ will be even. May2 comment Non-independent two consecutive draws from two urns You can use $E[Y] = E[E[Y|X]]$ and $Var[Y] = Var[E[Y|X]] + E[Var[Y|X]]$ to get simpler summations for the mean and variance. Apr29 comment Graph with 5 vertices - # of spanning trees Number of trees with one node of degree $3$ and one of degree $2$ is $5.4.3$ (picking nodes of degrees $3$ and $2$ and picking which node is connected to degree $2$ node). This makes it a total of $125$ ($=5^3$ as expected from Cayley's formula)