English

Curious congruences for Fibonacci numbers

Number Theory 2009-12-20 v4 Combinatorics

Abstract

In this paper we establish some sophisticated congruences involving central binomial coefficients and Fibonacci numbers. For example, we show that if p2,5p\not=2,5 is a prime then k=0p1F2k(2kk)=(1)[p/5](1(p/5))(modp2)\sum_{k=0}^{p-1}F_{2k}\binom{2k}{k}=(-1)^{[p/5]}(1-(p/5)) (mod p^2) and k=0p1F2k+1(2kk)=(1)[p/5](p/5)(modp2).\sum_{k=0}^{p-1}F_{2k+1}\binom{2k}k=(-1)^{[p/5]}(p/5) (mod p^2). We also obtain similar results for some other second-order recurrences and raise several conjectures.

Keywords

Cite

@article{arxiv.0912.2671,
  title  = {Curious congruences for Fibonacci numbers},
  author = {Zhi-Wei Sun},
  journal= {arXiv preprint arXiv:0912.2671},
  year   = {2009}
}

Comments

16 pages. Revise Conj. 4.2

R2 v1 2026-06-21T14:23:35.765Z