View Proposal #548

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ID548
First NameChristian
Last NameRoettger
InstitutionIowa State University
Speaker Categoryfaculty
Title of TalkBalanced Numbers and Balanced Primes
AbstractBalanced numbers are odd natural numbers n which have an equal number of 0s and 1s in the periodic part of the base-2 representation of their reciprocal 1/n. We present some insights about balanced numbers that use just elementary Number Theory like the Quadratic Reciprocity Theorem. In particular, if a prime p is congruent to 3 or 5 modulo 8, then p is balanced. If a prime p is congruent to 7 modulo 8, then p is not balanced. All powers of p are balanced iff p is. The case of primes congruent to 1 modulo 8 is much more difficult. Hasse made a breakthrough in 1966, showing that the balanced primes have a Dirichlet density of 17/24. We have refined Hasse's result slightly. Another question is how big is the set of balanced numbers (not only primes) less than x? Using a method due to Landau, we can show that this is bounded above by C x/log^(1/4) (x) and below by D x / log^(3/4)(x), with constants C, D > 0. I solemnly promise that I won't go into the gory detail, only highlight the beautiful and accessible parts of the subject. The second part of the talk is joint work with Joshua Zelinsky.
Subject area(s)
Suitable for undergraduates??
Day PreferenceSaturdayMild
Computer Needed?
Bringing a laptop?
Overhead Needed?
Software requests
Special Needs
Date Submitted2019-10-13 11:23:57
Year2019