It was shown by Abrham that the number of pure Skolem sequences of order \(n\), \(n \equiv 0\) or \(1 \pmod{4}\), and the number of extended Skolem sequences of order \(n\), are both bounded below by \(2^{\left\lfloor \frac{n}{3} \right\rfloor}\). These results are extended to give similar lower bounds for the numbers of hooked Skolem sequences, split Skolem sequences, and split-hooked Skolem sequences.
1970-2025 CP (Manitoba, Canada) unless otherwise stated.