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 A030638 #27 May 05 2023 08:41:14 %S A030638 240,336,432,528,560,624,648,810,816,880,912,1040,1104,1134,1232,1360, %T A030638 1392,1456,1488,1520,1536,1776,1782,1840,1904,1968,2000,2064,2106, %U A030638 2128,2256,2288,2320,2480,2544,2560,2576,2754,2832,2835,2928 %N A030638 Numbers with 20 divisors. %C A030638 Numbers of the form p^19, p*q^9 (A179692), p*q*r^4 (A179644) or p^3*q^4 (A179666), where p, q and r are distinct primes. - _R. J. Mathar_, Mar 01 2010 %H A030638 R. J. Mathar, <a href="/A030638/b030638.txt">Table of n, a(n) for n = 1..1000</a> %t A030638 Select[Range[20000],DivisorSigma[0,#]==20&] (* _Vladimir Joseph Stephan Orlovsky_, May 05 2011 *) %o A030638 (PARI) is(n)=numdiv(n)==20 \\ _Charles R Greathouse IV_, Jun 19 2016 %Y A030638 Cf. A030636, A030637, A137484. %K A030638 nonn %O A030638 1,1 %A A030638 _Jeff Burch_