The Fibonacci-index formula conjecture for earliest progressions

From papers

Let FnF_n denote the Fibonacci numbers. For a positive integer difference dd, let i(d)i(d) be the starting position of the first monochromatic arithmetic progression of difference dd having maximum length. Empirical evidence suggests that

The Fibonacci-index formula conjecture.

i(F2n+1)=F2n+32,i(F_{2n+1})=F_{2n+3}-2,

and

i(F2n)=F4n1.i(F_{2n})=F_{4n}-1.

The formulas concern the case d=Fnd=F_n, where the corresponding longest-progression lengths A(Fn)A(F_n) are not eventually constant. The paper explains that this prevents the authors from checking the identities automatically with their stated method, so the conjecture remains open.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Gandhar Joshi and Dan Rust, “Monochromatic arithmetic progressions in the Fibonacci, Thue-Morse, and Rudin-Shapiro words”, arXiv:2501.05830 (2025).

Solutions 0

No solutions have been posted yet.