This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A324333 #8 May 31 2024 22:05:04 %S A324333 1,2,4,6,11,12,14,16,18,20,21,22,24,25,27,29,30,32,34,35,36,38,39,41, %T A324333 42,43,44,45,47,50,51,52,53,54,56,57,58,59,60,64,66,67,68,69,70,71,72, %U A324333 73,74,75,76,77,79,81,83,84,85,86,87,88,89,90,91,92,93,94,95,97,98,100 %N A324333 Numbers d such that A324331(x) = d^2 only when x is a squarefree semiprime (A006881). %C A324333 Problem posed by Albert A. Mullin, who asks if this sequence is infinite. %H A324333 B. Alspach, <a href="https://doi.org/10.1016/0012-365X(82)90195-9">Research problems, Problem 18</a>, Discrete Math 40 (1982), page 126. %Y A324333 Cf. A000010, A000203, A006881. %Y A324333 Cf. A324331, A324334 (complement). %K A324333 nonn %O A324333 1,2 %A A324333 _Michel Marcus_, Feb 23 2019