Q-bonacci words and numbers
Résumé
We present a quite curious generalization of multi-step Fibonacci
numbers. For any positive rational $q$, we enumerate binary words
of length $n$ whose maximal factors of the form $0^a1^b$ satisfy $a
= 0$ or $aq > b$. When $q$ is an integer we rediscover classical
multi-step Fibonacci numbers: Fibonacci, Tribonacci, Tetranacci,
etc. When $q$ is not an integer, obtained recurrence relations are
connected to certain restricted integer compositions. We also
discuss Gray codes for these words, and a possibly novel
generalization of the golden ratio.