The article is devoted to the expansion of iterated Stratonovich stochastic
integrals of multiplicity 2 on the base of the combined approach of generalized
multiple and iterated Fourier series. We consider two different parts of the
expansion of iterated Stratonovich stochastic integrals. The mean-square
convergence of the first part is proved on the base of generalized multiple
Fourier series converging in the mean-square sense in the space L2​([t,T]2). The mean-square convergence of the second part is proved on the base of
generalized iterated (double) Fourier series converging pointwise. At that, we
prove the iterated limit transition for the second part of the expansion on the
base of the classical theorems of mathematical analysis. The results of the
article can be applied to the numerical integration of Ito stochastic
differential equations.Comment: 18 pages. Sect. 3 was added. arXiv admin note: text overlap with
arXiv:1801.05654, arXiv:1801.00784, arXiv:1801.01564, arXiv:1712.09746,
arXiv:1801.03195, substantial text overlap with arXiv:1712.0951