English

On the diophantine equation $An!+Bm!=f(x,y)$

Number Theory 2023-09-27 v1 Algebraic Geometry

Abstract

Erd\"os and Obl\'ath proved that the equation n!±m!=xpn!\pm m!=x^p has only finitely many integer solutions. More general, under the ABC-conjecture, Luca showed that P(x)=An!+Bm!P(x)=An!+Bm! has finitely many integer solutions for polynomials of degree 3\geq 3. For certain polynomials of degree 2\geq 2, this result holds unconditionally. We consider irreducible homogeneous f(x,y)Q[x,y]f(x,y)\in \mathbb{Q}[x,y] of degree 2\geq 2 and show that there are only finitely many n,mn,m such that An!+Bm!An!+Bm! is represented by f(x,y)f(x,y). As corollaries we get alternative proofs for the unconditional results of Luca. We also discuss the case of certain reducible f(x,y)f(x,y). Furthermore, we study equations of the form n!!m!!=f(x,y)n!!m!!=f(x,y) and n!!m!!=f(x)n!!m!!=f(x).

Keywords

Cite

@article{arxiv.2309.15007,
  title  = {On the diophantine equation $An!+Bm!=f(x,y)$},
  author = {Saša Novaković},
  journal= {arXiv preprint arXiv:2309.15007},
  year   = {2023}
}

Comments

12 pages, comments are welcome! arXiv admin note: substantial text overlap with arXiv:2308.11002