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 A281663 #12 Jan 27 2017 13:20:39 %S A281663 1,8,12,40,56,225,441 %N A281663 Refactorable numbers that are not the sum of two refactorable numbers. %C A281663 Is this sequence finite? %H A281663 S. Colton, <a href="https://cs.uwaterloo.ca/journals/JIS/colton/joisol.html">Refactorable Numbers - A Machine Invention</a>, J. Integer Sequences, Vol. 2, 1999. %H A281663 Joshua Zelinsky, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL5/Zelinsky/zelinsky9.html">Tau Numbers: A Partial Proof of a Conjecture and Other Results </a>, Journal of Integer Sequences, Vol. 5 (2002), Article 02.2.8 %e A281663 40 is a term because 40 is a refactorable number and there is no partition of 40 into two refactorable parts. %o A281663 (PARI) isrefac(n) = (n%numdiv(n))==0; %o A281663 isok(n) = isrefac(n) && (sum(k=1, n\2, isrefac(k) && isrefac(n-k)) == 0); \\ _Michel Marcus_, Jan 26 2017 %Y A281663 Cf. A033950, A172398, A280634. %K A281663 nonn,more %O A281663 1,2 %A A281663 _Altug Alkan_, Jan 26 2017