منابع مشابه
B2[g]SEQUENCES WHOSE TERMS ARE SQUARES
INTRODUCTION Sixty years ago Sidon [7] asked, in the course of some investigations of Fourier series, for a sequence a1 < a2... for which the sums ai + aj are all distinct and for which ak tends to infinity as slowly as possible. Sidon called these sequences, B2 sequences. The greedly algorithm gives ak ¿ k and this was the best result until Atjai, Komlos and Szemeredi [1] found a B2 sequence s...
متن کاملBipartite Graphs whose Squares are not Chromatic-Choosable
The square G2 of a graph G is the graph defined on V (G) such that two vertices u and v are adjacent in G2 if the distance between u and v in G is at most 2. Let χ(H) and χl(H) be the chromatic number and the list chromatic number of H, respectively. A graph H is called chromatic-choosable if χl(H) = χ(H). It is an interesting problem to find graphs that are chromatic-choosable. Motivated by th...
متن کاملOn Points Whose Coordinates Are Terms of a Linear Recurrence*
Let R = {Rn}TM be a second-order recurrent sequence (generalized Fibonacci sequence) of integers defined by Rn = ARn_l-BRn_2 (forn>l), where the initial terms are R$ = 0, Rx = 1, and A and B are fixed nonzero integers. Let a and j8 be the roots of the characteristic polynomial x Ax + B. We will assume that the discriminant D = A -AB > 0 and D is not a perfect square. From this, it follows that ...
متن کاملModules whose direct summands are FI-extending
A module $M$ is called FI-extending if every fully invariant submodule of $M$ is essential in a direct summand of $M$. It is not known whether a direct summand of an FI-extending module is also FI-extending. In this study, it is given some answers to the question that under what conditions a direct summand of an FI-extending module is an FI-extending module?
متن کاملSome Families of Graphs whose Domination Polynomials are Unimodal
Let $G$ be a simple graph of order $n$. The domination polynomial of $G$ is the polynomial $D(G, x)=sum_{i=gamma(G)}^{n} d(G,i) x^{i}$, where $d(G,i)$ is the number of dominating sets of $G$ of size $i$ and $gamma(G)$ is the domination number of $G$. In this paper we present some families of graphs whose domination polynomials are unimodal.
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ژورنال
عنوان ژورنال: Acta Arithmetica
سال: 1990
ISSN: 0065-1036,1730-6264
DOI: 10.4064/aa-55-3-261-265