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Integer Complexity: Breaking the θ(n2) barrier

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TLDR
An algorithm with Θ(n log 2 3) as its running time is presented and a proof of the theorem is presented: the largest solutions of f (m) = 3k, 3k±1 are, respectively, m = 3 k , 3 k ± 3 k−1.
Abstract
—The integer complexity of a positive integer n, denoted f (n), is defined as the least number of 1's required to represent n, using only 1's, the addition and multiplication operators, and the parentheses. The running time of the algorithm currently used to compute f (n) is Θ(n 2). In this paper we present an algorithm with Θ(n log 2 3) as its running time. We also present a proof of the theorem: the largest solutions of f (m) = 3k, 3k±1 are, respectively, m = 3 k , 3 k ± 3 k−1 .

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Journal ArticleDOI

Numbers with Integer Complexity Close to the Lower Bound

Harry Altman, +1 more
- 01 Dec 2012 - 
TL;DR: In this paper, it was shown that f(2m3k) = 2m + 3k for m ≤ 31 with m and k not both zero, and the same for larger m.
Posted Content

Algorithms for determining integer complexity

TL;DR: Three algorithms to compute the complexity of all natural numbers, each superior to the one in [11], are presented and it is shown that they run in time $O(N^\alpha)$ and space $N\log\log N)$.
Dissertation

Integer Complexity, Addition Chains, and Well-Ordering.

Harry Altman
TL;DR: Two notions of the “complexity” of a natural number are considered, the first being addition chain length, and the second known simply as “integer complexity”, which is the smallest number of 1’s needed to write n using an arbitrary combination of addition and multiplication.
Journal Article

Integer Complexity: Algorithms and Computational Results.

Harry Altman
- 01 Jan 2018 - 
TL;DR: In this paper, an algorithm for computing stable numbers is presented, which is based on considering the defect of a number, defined by δ(n):=\|n\|-3\log_3 n, building on the methods presented in [3] and [4].
Journal ArticleDOI

A short note on integer complexity

TL;DR: This short note gives a new, constructive upper bound on the smallest number of 1's needed in conjunction with arbitrarily many +, *, and parentheses to write an integer n for generic integers n.
References
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Journal Article

The On-Line Encyclopedia of Integer Sequences.

TL;DR: The On-Line Encyclopedia of Integer Sequences (OEIS) as mentioned in this paper is a database of 13,000 number sequences and is freely available on the Web (http://www.att.com/~njas/sequences/) and is widely used.
Book ChapterDOI

The On-Line Encyclopedia of Integer Sequences

TL;DR: The On-Line Encyclopedia of Integer Sequences (or OEIS) is a database of some 130000 number sequences which serves as a dictionary, to tell the user what is known about a particular sequence and is widely used.
Book

Unsolved Problems in Number Theory

TL;DR: In this article, a discussion of hundreds of open questions, organized into 185 different topics, represent aspects of number theory and are organized into six categories: prime numbers, divisibility, additive number theory, Diophantine equations, sequences of integers, and miscellaneous.
Journal ArticleDOI

Unsolved problems in number theory

TL;DR: The topics covered are: additive representation functions, the Erdős-Fuchs theorem, multiplicative problems (involving general sequences), additive and multiplicative Sidon sets, hybrid problems (i.e., problems involving both special and general sequences, arithmetic functions and the greatest prime factor func- tion and mixed problems.
Journal ArticleDOI

Some Suspiciously Simple Sequences

TL;DR: Some Suspiciously Simple Sequences The American Mathematical Monthly: Vol 93, No 3, pp 186-190 as discussed by the authors, was published in 1986, and is a classic example.
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