Research Article | Open Access

Nipen Saikia, "Some New Explicit Values of Parameters and of Quotients of Eta-Function", *International Scholarly Research Notices*, vol. 2013, Article ID 435261, 8 pages, 2013. https://doi.org/10.1155/2013/435261

# Some New Explicit Values of Parameters and of Quotients of Eta-Function

**Academic Editor:**T. Allahviranloo

#### Abstract

We find some new explicit values of the parameters and of quotients of eta-function by using Ramanujan's class invariants.

#### 1. Introduction

For and , the Dedekind eta-function and Ramanujan’s function are defined by where .

In page 212 of his lost notebook [1], Ramanujan defined and provided a list of eleven recorded and ten unrecorded values of for positive integers . All 21 values of and many more were established by Berndt et al. [2] by using the modular -invariant, modular equations, Kronecker’s limit formula, and the explicit Shimura reciprocity law. An account of this can also be found in Chapter 9 of [3]. Closely related to is the parameter introduced by Ramanathan [4] and is defined as Yi [5, 6] also found several values of parameters and by finding the explicit values of her parameters and , defined by where and are positive real numbers. In fact, , and . Baruah and Saikia [7, 8] also evaluated several new values of and . A generalization of has been studied by Naika et al. [9]. Here we give a list of the values of for which and were evaluated in [1, 2, 5–8] without referring them specifically to avoid repetitions. The values of for which were evaluated in the literature are = 1, 3, 5, 7, 9, 11, 13, 15, 5/3, 17, 25, 33, 41, 49, 57, 65, 81, 89, 73, 97, 121, 169, 193, 217, 241, 265, 289, 361, 11/3, and 19/3, and the values of values of for which were evaluated in literature are = 1, 2, 3, 4, 5, 6, 3/2, 7, 8, 9, 10, 5/2, 11, 13, 14, 7/2, 15, 5/3, 17, 19, 20, 5/4, 22, 11/2, 25, 26, 13/2, 44, 11/4, and 49. We also note from [2, page 281] and [7, page 43, Theorem 4.2] that respectively.

In this paper we find further new values of and by using Ramanujan’s class invariants which are defined as where . In particular, we evaluate values of for = 23, 31, 47, 59, 71, 2, 4, 6, 10, 5/2, 14, and 7/2 and new values of for = 23, 31, 47, 59, and 71. It worth to mention here that for the first time in this paper explicit values of for some even values of are evaluated. Previously, Berndt et al. [2] calculated explicit values of , , and by using Ramanujan’s class invariants. An account of Ramanujan’s class invariants can be found in Berndt’s book [10]. For further references on Ramanujan’s class invariants refer see [11–14].

The explicit values of the functions and can be applied to find explicit values of Ramanujan’s cubic continued fraction defined by We refer to [7] for details. To this end we define a general parameter [14, page 2, equation (10)] for all positive real numbers and and connected with parameters , , and Ramanujan’s class invariants as Saikia [14] studied several properties of the parameter and evaluated many explicit values of by using Ramanujan’s modular equations. From [14, page 4, Theorem 16(iii)], we also note here that .

In Section 2, we record some preliminary results, and in Section 3 we evaluate new values of the parameters and .

#### 2. Preliminaries

Lemma 1 (see [3, page 203, Theorem 9.3.1]). *One has
*

Lemma 2 (see [14, page 4, Theorem 22(i)]). *One has
*

Lemma 3. *One has
*

*Proof. *We set in Lemma 2 and apply Lemma 1 to complete the proof.

Lemma 4. *One has
*

This readily follows from [2, page 9, equation (3.4)] or [3, page 203, equation (9.3.4)].

Lemma 5. *One has
*

*Proof. *From [11, page 123, equation (4.14)], we note that
Replacing by in (14) and squaring, we arrive at desired result.

Lemma 6. *One has
*

For (15), (16), (17) and (18) see [10, page 342]. For (19), (20), and (21) see [10, page 227, equation (5.8)], [10, page 229, equation (5.16)], and [10, page 257, equation (6.61)]. For (22) and (23) see [14, page 5, Corollary 24(i & ii))].

Lemma 7. *One has
*

For (24) to (27) see [12]. Equation (28) follows from the values of and from [10, page 200].

Lemma 8. *One has
*

*Proof. *From [15, page 124], we note that
Employing (30) in (6) and simplifying, we deduce that
From [15, page 230, Entry 5(ii)], we note that
where has degree 3 over .

Combining (31) and (32) and simplifying, we deduce that
From [10, page 187, Entry 2.2], we note that
Employing (34) in (33), and simplifying, we find that
Solving (35) for , we arrive at the desired result.

Lemma 9. *One has
*

*Proof. *We set = 10/3, 2/15, 14/3, 6/7, and 6/3 in Lemma 8 and employ the corresponding values of from Lemma 7 to complete the proof.

#### 3. New Values of and

The section is devoted to evaluate new values of and .

Theorem 10. *One has
*

*Proof. *Employing (19) in Lemma 3 with , we have
From (42), we deduce that
Setting in Lemma 4, employing (43), and solving the resulting equation, we find that
Multiplying (42) and (44) and simplifying, we easily calculate the value of , and dividing (44) by (42) and simplifying we evaluate the value of .

*Remark 11. *The values of and also follow from (5) and the values of and , respectively.

Theorem 12. *One has
*

*Proof. *Employing (20) in Lemma 3 with , we have
From (46), we deduce that
Setting in Lemma 4, employing (47), and solving the resulting equation, we obtain
Multiplying (46) and (48) and simplifying, we easily calculate the value of , and dividing (48) by (46) and simplifying we evaluate the value of .

*Remark 13. *The values of and also follow from (5) and the values of and , respectively.

Theorem 14. *One has*

*Proof. *Employing (21) in Lemma 3 with , we have
From (50), we deduce that
Setting in Lemma 4, employing (51), and solving the resulting equation, we obtain
Combining (50) and (52) we easily evaluate the values of and .

*Remark 15. *The values of and also follow from (5) and the values of and , respectively.

Theorem 16. *One has
*

*Proof. *Combining (15), (16) and Lemma 3, we deduce that
From (54), we find that
Setting in Lemma 4, employing (55), and solving the resulting equation, we obtain
Combining (54) and (56) we easily evaluate the values of and .

*Remark 17. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 18. *One has
*

*Proof. *Combining (17), (18) and Lemma 3, we deduce that
From (58), we find that
Setting in Lemma 4, employing (59), and solving the resulting equation, we obtain
Combining (58) and (60) we easily calculate the values of and .

*Remark 19. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Next, we evaluate some values of and for even values of . The values of are new. The values of are classical, but the method of evaluations is new.

Theorem 20. *One has
*

*Proof. *Combining (22) and Lemma 3 with , we note that
From (62), we deduce that
Setting in Lemma 4, employing (63), and solving the resulting equation, we obtain
Combining (62) and (64) we easily evaluate the values of and .

*Remark 21. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 22. *One has
*

*Proof. *Combining (23) and Lemma 3 with , we note that
From (66), we deduce that
Setting in Lemma 4, employing (67), and solving the resulting equation, we obtain
Combining (66) and (68) we easily evaluate the values of and .

*Remark 23. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 24. *One has
**
where
*

*Proof. *Employing (40) in Lemma 5 with , solving the resulting equation, and noting the result from Lemma 3, we obtain
where
Employing (71) in Lemma 4 and solving the resulting equation, we obtain
where
Combining (71) and (73) we calculate the values of and .

*Remark 25. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 26. *One has
**
where*

*Proof. *Employing (36) in in Lemma 5 with , solving the resulting equation, and noting the result from Lemma 3, we obtain
whereEmploying (77) in Lemma 4 and solving the resulting equation, we obtain
whereCombining (77) and (79) we calculate the values of and .

*Remark 27. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 28. *One has
**
where*

*Proof. *Employing (37) in in Lemma 5 with , solving the resulting equation, and noting the result from Lemma 3, we obtain
whereEmploying (83) in Lemma 4 and solving the resulting equation, we obtain
where
Combining (83) and (85) we calculate the values of and .

*Remark 29. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 30. *One has
**
where*

*Proof. *Employing (38) in in Lemma 5 with , solving the resulting equation, and noting the result from Lemma 3, we obtain
whereEmploying (89) in Lemma 4 and solving the resulting equation, we obtain
whereCombining (89) and (91) we calculate the values of and .

*Remark 31. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

Theorem 32. *One has
**
where*

*Proof. *Employing (39) in Lemma 5 with , solving the resulting equation, and noting the result from Lemma 3, we obtain
whereEmploying (95) in Lemma 4 and solving the resulting equation, we obtain
whereCombining (95) and (97) we calculate the values of and .

*Remark 33. *The values of and can easily be calculated by employing the values of and , respectively, in (5).

*Remark 34. *(i) From (36) and (77) we can easily deduce the values of class invariants and . (ii) Combining (37) and (83) we can calculate the values of class invariants and . (iii) The values of class invariants and can be calculated from (38) and (89). (iv) Combining (39) and (95) we can obtain the values of class invariants and . (v) Combining (40), (71), and Lemma 3 we can calculate the values of class invariants and .

#### Acknowledgment

The author is thankful to University Grants Commission, New Delhi, India, for partially supporting the research work under the Grant no. F. No. 41-1394/2012(SR).

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#### Copyright

Copyright © 2013 Nipen Saikia. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.