An Introduction to OEIS Sequence A395620

This paper presents an introduction to the integer sequence A395620 from the Online Encyclopedia of Integer Sequences (OEIS). The sequence counts permutations of the set {1, 2, ..., n} whose prefix sums never form a perfect square. The work describes the definition of the sequence, provides examples illustrating the counting condition, and discusses its connection with combinatorics and number theory. The problem belongs to the study of restricted permutations, where arithmetic constraints influence the structure and enumeration of combinatorial objects. The paper highlights the mathematical interest of sequence A395620 and suggests possible directions for further investigation, including more efficient counting methods, asymptotic analysis, and connections with other classes of constrained permutations.