English

Alternating "strange" functions

Number Theory 2017-06-14 v2

Abstract

In this note we consider infinite series similar to the "strange" function F(q)F(q) of Kontsevich studied by Zagier, Bryson-Ono-Pitman-Rhoades, Bringmann-Folsom-Rhoades, Rolen-Schneider, and others in connection to quantum modular forms. We show that a class of "strange" alternating series that are well-defined almost nowhere in the complex plane can be added (using a modified definition of limits) to familiar infinite products to produce convergent qq-hypergeometric series, of a shape that specializes to Ramanujan's mock theta function f(q)f(q), Zagier's quantum modular form σ(q)\sigma(q), and other interesting number-theoretic objects. We also discuss Ces\`{a}ro sums for these alternating series, and continued fractions that are similarly "strange".

Keywords

Cite

@article{arxiv.1701.05126,
  title  = {Alternating "strange" functions},
  author = {Robert Schneider},
  journal= {arXiv preprint arXiv:1701.05126},
  year   = {2017}
}

Comments

5 pages, updated draft with revised title and exposition, and additional corollaries

R2 v1 2026-06-22T17:53:22.944Z