Modular equations of a continued fraction of order six

Yoonjin Lee, Yoon Kyung Park

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3 Scopus citations


We study a continued fraction X(τ) of order six by using the modular function theory. We first prove the modularity of X(τ), and then we obtain the modular equation of X(τ) of level n for any positive integer n; this includes the result of Vasuki et al. for n = 2, 3, 5, 7 and 11. As examples, we present the explicit modular equation of level p for all primes p less than 19. We also prove that the ray class field modulo 6 over an imaginary quadratic field K can be obtained by the value X 2 (τ). Furthermore, we show that the value 1/X(τ) is an algebraic integer, and we present an explicit procedure for evaluating the values of X(τ) for infinitely many τ's in K.

Original languageEnglish
Pages (from-to)202-219
Number of pages18
JournalOpen Mathematics
Issue number1
StatePublished - 2019

Bibliographical note

Publisher Copyright:
© 2019 Lee and Park, published by De Gruyter 2019.


  • Ramanujan continued fraction
  • modular equation
  • modular function
  • ray class fields


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