Padovan, Pascal, and Proofs without Words
David Nacin, William Patterson University
Date & time: Thursday, 04 March 2021 at 5:00PM - 6:00PM
Abstract: What happens when we attempt to construct the Fibonacci spiral with triangles instead of squares? We get a new sequence, the Padovan sequence, which answers its own collection of unique and beautiful counting problems. In this talk we will show how this construction defines this sequence and then rediscover the same sequence hiding again in other surprising places. We then prove several identities without using either words or numbers, by considering triangles composed of colored dots.
The Fibonacci sequence is connected to the golden ratio which arises from a simple question about rectangles and proportion. A slightly different natural question leads to a new ratio and yet another method for defining our sequence. We then observe the uses of this sequence and its ratio in architecture and discuss the history behind the patterns we've uncovered. We conclude with a counterexample to a conjecture about this sequence that leads us to a final construction involving copies of the Fibonacci sequence itself.