n + 1. In particular, they determined the existence status of almost p-ary perfect sequences
of period n + 1 for 3 ≤ n ≤ 100, except some open cases (see Table 2 [2]). This open cases
lead the authors to their question (see Question 1 in [2]), that we quote: … We recall that if
p is prime and there exists an almost p-ary perfect sequence of period n + 1, then p|(n − 1)
(see Corollary 1 in [2], or Theorem 2 below). Hence, the condition p|(n − 1) in Question 1 is …