# Seminars & Colloquia Calendar

## Trees, Fibonacci Numbers, and Nested Recurrences

#### Nathan Fox, College of Wooster

Location: ** Hill 705**

Date & time: Thursday, 07 March 2019 at 5:00PM - 6:00PM

*Abstract:* Conolly's sequence (A046699) is defined by the nested recurrence relation C(n)=C(n-C(n-1))+C(n-1-C(n-2)) and the initial conditions C(1)=C(2)=1. This sequence is monotone increasing with each positive integer appearing at least once, a property known in the literature as slow. Conolly's sequence and several other slow sequences generated by nested recurrences are known to have combinatorial interpretations in terms of enumerating leaves in infinite tree structures. For the Conolly sequence, the tree-based interpretation illuminates an intimate connection between the sequence and the powers of two. In fact, the Conolly sequence has an alternate, purely number-theoretic definition based on powers of two. Replacing powers of two with Fibonacci numbers in this construction yields a different slow sequence (A316628). In this talk, we will describe the three different ways of constructing the Conolly sequence (recurrence, number theory, trees) and show why they all yield the same sequence. Then we will construct this new sequence based on the Fibonacci numbers, which also is slow, has a tree-based interpretation, and satisfies a nested recurrence. If time permits, we will describe how to generalize the construction to discover many new integer sequences.

Eilidh McKemmie -Charles Weibel Organizer's Page

Narek Hovsepyan and Ewerton Rocha Vieira Organizer's page

Ziming Shi, Sagun Chanillo, Xiaojun Huang, Chi Li, Jian Song Seminar website Old seminar website

Sepehr Assadi Seminar webpage

Jeffry Kahn, Bhargav Narayanan, Jinyoung Park Organizer's webpage

Robert Dougherty-Bliss and Doron Zeilberger --> homepage

Paul Feehan, Daniel Ketover, Natasa Sesum Organizer's webpage

Lev Borisov, Emanuel Diaconescu, Angela Gibney, Nicolas Tarasca, and Chris Woodward Organizer's webpage

Hong Chen Seminar webpage

Fanxin Wu and Nkhalo Malawo Organizer's website

James Holland; Organizer website

Organizers: Maxime Van de Moortel and Avy Soffer. Organizer's Page

Yanyan Li, Zheng-Chao Han, Jian Song, Natasa Sesum Organizer's Webpage

Organizer: Luochen Zhao

Yanyan Li, Zheng-Chao Han, Natasa Sesum, Jian Song Organizer's Page

Lisa Carbone, Yi-Zhi Huang, James Lepowsky, Siddhartha Sahi Organizer's webpage

Simon Thomas website

Kasper Larsen, Daniel Ocone and Kim Weston Organizer's page

Joel Lebowitz, Michael Kiessling

Yanyan Li, Dennis Kriventsov Organizer's Webpage

Alex V. Kontorovich, Vlada Sedláček seminar website

Stephen D. Miller

Organizers: Yanyan Li, Z.C. Han, Jian Song, Natasa Sesum

Kristen Hendricks, Xiaochun Rong, Hongbin Sun, Chenxi Wu Organizer's page

Fioralba Cakoni Seminar webpage

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