Congruences for Catalan-Larcombe-French numbers

TL;DR

This paper establishes new congruences for scaled Catalan-Larcombe-French numbers and proves their log-convexity, advancing understanding of their number-theoretic properties.

Contribution

It derives novel congruences for the sequence $S_n$ modulo prime powers and proves the log-convexity of the sequence, which are new results in the study of these numbers.

Findings

Derived congruences for $S_{mp^r}$, $S_{mp^r-1}$, and $S_{mp^r+1}$ modulo prime powers.

Proved that $S_{(p^2-1)/2} ot ot ot ext{divisible by } p^2$ for certain primes.

Established that the sequence $iglrace S_m igrrace$ is log-convex.

Abstract

Let $\{P_n\}$ be the Catalan-Larcombe-French numbers given by $P_0=1,\ P_1=8$ and $n^2P_n=8(3n^2-3n+1)P_{n-1}-128(n-1)^2P_{n-2}$ $(n\ge 2)$, and let $S_n=P_n/2^n$. In this paper we deduce congruences for $S_{mp^r}\pmod{p^{r+2}}$, $S_{mp^r-1}\pmod{p^r}$ and $S_{mp^r+1}\pmod{p^{2r}}$, where $p$ is an odd prime and $m,r$ are positive integers. We also prove that $S_{(p^2-1)/2}\equiv 0\pmod {p^2}$ for any prime $p\equiv 5,7\pmod 8$, and show that $\{S_m\}$ is log-convex.