1. Collected Papers of Srinavasa Ramanujan (Cambridge, 1927), p. 332, Q. 738.
2. Ibid., p. 329, Q. 526.
3. Knopp,Infinite Series, p. 430.
4. In what followsw stands for a number between 0 and 1 andt for a number ⩾ 1 (2) specifies the relation between the two.
5. Iff″ (x) keeps the same sign, then any line cuts the curvey =f (x) in two points only.