# Volume 26 (2018), Issue 1

### 1. On Self-Similar Subgroups in the Sense of IFS

In this paper, we first give several properties with respect to subgroups of self-similar groups in the sense of iterate function system (IFS). We then prove that some subgroups of p-adic numbers ℚp are strong self-similar in the sense of IFS.

### 2. On xn + yn = n!zn

In p. 219 of R.K. Guy's Unsolved Problems in Number Theory, 3rd edn., Springer, New York, 2004, we are asked to prove that the Diophantine equation xn + yn = n!zn has no integer solutions with n ∈ N+ and n &gt; 2. But, contrary to this expectation, we show that for n = 3, this equation has in finitely many primitive integer solutions, i.e. the solutions satisfying the condition gcd(x, y, z) = 1.

### 3. Nonlinear *-Lie Higher Derivations of Standard Operator Algebras

Let ℌ be an in finite-dimensional complex Hilbert space and A be a standard operator algebra on ℌ which is closed under the adjoint operation. It is shown that every nonlinear *-Lie higher derivation D = {δn}gn∈N of A is automatically an additive higher derivation on A. Moreover, D = {δn}gn∈N is an inner *-higher derivation.

### 4. The Properties of the Weighted Space Hk2,α (Ω) and Weighted Set Wk2,α(Ω, δ)

We study the properties of the weighted space Hk 2α(Ω) and weighted set Wk 2α(Ω, δ)for boundary value problem with singularity.

### 5. Area Nevanlinna Type Classes of Analytic Functions in the Unit Disk and Related Spaces

The survey collects many recent advances on area Nevanlinna type classes and related spaces of analytic functions in the unit disk concern- ing zero sets and factorization representations of these classes and discusses approaches, used in proofs of these results.