English

Ramanujan's Harmonic Number Expansion into Negative Powers of a Triangular Number

Classical Analysis and ODEs 2007-07-30 v2 General Mathematics

Abstract

An algebraic transformation of the DeTemple-Wang half-integer approximation to the harmonic series produces the general formula and error estimate for the Ramanujan expansion for the nth harmonic number into negative powers of the nth triangular number. We also discuss the history of the Ramanujan expansion for the nth harmonic number as well as sharp estimates of its accuracy, with complete proofs, and we compare it with other approximative formulas.

Keywords

Cite

@article{arxiv.0707.3950,
  title  = {Ramanujan's Harmonic Number Expansion into Negative Powers of a Triangular Number},
  author = {Mark B. Villarino},
  journal= {arXiv preprint arXiv:0707.3950},
  year   = {2007}
}

Comments

sharp error estimates and general formulas for Ramanujan's harmonic number expansion; correction of typo in the Ramanujan-Lodge lower bound constant; thanks to Jonathan Post and Martin Fuller; fixed typo in the title

R2 v1 2026-06-21T09:02:07.264Z