English

On a Question of Lehmer concerning the Comtet Numbers

Number Theory 2026-07-29 v1 Combinatorics

Abstract

The Comtet numbers b(n,k)b(n,k) and B(n,k)B(n,k) of the first and second kind arise from the powers of (1+x)log(1+x)(1+x)\log(1+x) and of its compositional inverse, respectively. By interpreting both families as special values of weighted Stirling polynomials, we answer Lehmer's question of whether B(n,k)B(n,k) satisfies a recurrence with a fixed number of terms by proving the four-term recurrence kB(n+1,k+1)=B(n,k1)(nk)B(n,k)B(n+1,k)kB(n+1,k+1)=B(n,k-1)-(n-k)B(n,k)-B(n+1,k). The corresponding relation for the unsigned array was conjectured by M. Kurkov, but not proved, in OEIS A354794. We further derive explicit formulas, convolution identities, and differential-difference relations for the Touchard-type polynomials attached to the two families.

Keywords

Cite

@article{arxiv.2607.26613,
  title  = {On a Question of Lehmer concerning the Comtet Numbers},
  author = {Sangtae Jeong},
  journal= {arXiv preprint arXiv:2607.26613},
  year   = {2026}
}

Comments

34 pages