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 A057265 #27 Sep 08 2022 08:45:02 %S A057265 2,8,12,18,24,40,56,60,72,80,84,88,96,104,108,128,132,136,152,156,180, %T A057265 184,204,228,232,240,248,252,276,288,296,328,344,348,360,372,376,384, %U A057265 396,424,444,448,450,468,472,480,488,492 %N A057265 Even refactorable numbers (i.e., the number of divisors is itself a divisor and it is also even). %C A057265 Invented by the HR mathematical theory formation program. %D A057265 S. Colton, Unpublished PhD Thesis, University of Edinburgh, 2000 %H A057265 Amiram Eldar, <a href="/A057265/b057265.txt">Table of n, a(n) for n = 1..10000</a> %H A057265 Simon Colton, <a href="http://www.cs.uwaterloo.ca/journals/JIS/colton/joisol.html">Refactorable Numbers - A Machine Invention</a>, J. Integer Sequences, Vol. 2, 1999, #2. %H A057265 Simon Colton, <a href="http://web.archive.org/web/20070831060523/http://www.dai.ed.ac.uk/homes/simonco/research/hr/">HR - Automatic Theory Formation in Pure Mathematics</a> %e A057265 18 is refactorable because tau(18) = 6 and 6 divides 18 and 18 is even. %t A057265 rfnQ[n_]:=Module[{ds=DivisorSigma[0,n]},Divisible[n,ds] && EvenQ[ds]];Select[Range[2,500,2],rfnQ] (* _Harvey P. Dale_, Mar 14 2011 *) %o A057265 (Magma) [k:k in [2..500 by 2]| IsIntegral(k/d) and IsEven(d) where d is #Divisors(k)]; // _Marius A. Burtea_, Jan 13 2020 %Y A057265 Cf. A033950, A036896. %K A057265 easy,nonn %O A057265 1,1 %A A057265 Simon Colton (simonco(AT)cs.york.ac.uk), Aug 21 2000 %E A057265 Corrected (erroneous term 36 removed) by _Harvey P. Dale_, Mar 14 2011