Questions tagged [integer-partitions]
Use this tag for questions related to ways of writing a positive integer as a sum of positive integers.
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Recurrence for the partition numbers
I'm reading Analytic Combinatorics [PDF] book by Flajolet and Sedgewick, and I can't figure out one of the steps in the derivation of the $P_n$ — number of partitions of size $n$ (or coefficients in ...
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On problems of coins totaling to a given amount
I don't know the proper terms to type into Google, so please pardon me for asking here first.
While jingling around a few coins, I realized that one nice puzzle might be to figure out which $n$ or so ...
user7055
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Putnam Problem: Partitioning integers with generating functions
We were given the following A-1 problem from the 2003 Putnam Competition:
Let $n$ be a fixed positive integer. How many ways are there to write $n$ as a sum of positive integers, $$ n= a_1+a_2+ \...
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Young projectors in Fulton and Harris
In Section 4 of Fulton and Harris' book Representation Theory, they give the definition of a Young tableau of shape $\lambda = (\lambda_1,\dots,\lambda_k)$ and then define two subgroups of $S_d$, the ...
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A "binomial" generalization of harmonic numbers
For positive integers $s$ and $n$ (let's limit the generality), define
$$H_s(n)=\sum_{k=1}^{n}\frac{1}{k^s},\qquad G_s(n)=\sum_{k=1}^{n}\binom{n}{k}\frac{(-1)^{k-1}}{k^s}.$$
The former is well-known; ...
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Seeking a textbook proof of a formula for the number of set partitions whose parts induce a given integer partition
Let $t \geq 1$ and $\pi$ be an integer partition of $t$. Then the number of set partitions $Q$ of $\{1,2,\ldots,t\}$ for which the multiset $\{|q|:q \in Q\}=\pi$ is given by \[\frac{t!}{\prod_{i \geq ...
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Expected Value for the Number of Parts of a Random Partition (Considering Only a Portion of the Partition Spectrum)
Let $n$ be a positive integer. If we take the set of all partitions of $n$ and choose a random partition from it (uniformly), then the expected value of the number of parts of this partition is a ...
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Maximal Zero Sums Partition
You are given $n$ numbers between $-n$ and $n$, the sum of numbers is $0$. Divide the given sequence on disjoint subsequences in such a way that each subsequence has zero sum. Each element should ...
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Recovering a partition of 50
The sum of 10 numbers, not necessarily distinct, is 50. When placed appropriately in the circles of this diagram, any two numbers will be joined by a line if, and only if, they have a common divisor ...
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Inequality for hook numbers in Young diagrams
Consider a Young diagram $\lambda = (\lambda_1,\ldots,\lambda_\ell)$. For a square $(i,j) \in \lambda$ define hook numbers $h_{ij} = \lambda_i + \lambda_j' -i - j +1$ and complementary hook numbers $...
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Closed form for $\sum_{n=1}^\infty \frac{1}{P(n)}$, where $P(n)$ is the partition function.
Is there a closed form for the following infinite series?
$$\sum_{n=1}^\infty \frac{1}{P(n)}=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{5}+...$$
where $P(n)$ is the partition function.
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How to prove it? (one of the Rogers-Ramanujan identities)
Prove the following identity (one of the Rogers-Ramanujan identities) on formal power series by interpreting each side as a generating function for partitions:
$$1+\sum_{k\geq1}\frac{z^k}{(1-z)(1-z^2)...
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Elementary proof of Ramanujan's "most beautiful identity"
Ramanujan presented many identities, Hardy chose one
which for him represented the best of Ramanujan. There are many proofs for this identity.
(for example, H. H. Chan’s proof, M. Hirschhorn's proof....
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Integral of products of cosines
Given $m+1$ integers $\alpha_0,\ldots,\alpha_m\geq 1$, I was trying to get a nice closed formula for the integral
$$
\int_0^\pi\cos(\alpha_1\theta)\cdots\cos(\alpha_m\theta)d\theta.
$$
More precisely, ...
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Characters of the symmetric group corresponding to partitions into two parts
Let $n\in\mathbb N$ be a natural number and $\lambda=(a,b)\vdash n$ a partition of $n$ into two parts, i.e. $a\ge b$ and $a+b=n$. In this special case, is there a simple description of the character $\...
user38451