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 A140645 #17 Jul 12 2025 22:44:09
%S A140645 1,2,4,6,3,6,9,12,6,3,9,6,9,9,12,9,15,9,9,18,9,9,9,9,18,18,9,18,18,18,
%T A140645 18,18,18,18,36,18,27,18,18,18,18
%N A140645 Digit sums of highly composite numbers.
%C A140645 Except for the first three terms, all others are multiples of 3.
%H A140645 Amiram Eldar, <a href="/A140645/b140645.txt">Table of n, a(n) for n = 1..10000</a>
%H A140645 Achim Flammenkamp, <a href="http://wwwhomes.uni-bielefeld.de/achim/highly.txt">Table of 1200 Highly Composite Numbers</a>.
%H A140645 Graeme McRae, <a href="https://web.archive.org/web/20190223125015/http://2000clicks.com/mathhelp/NumberFactorsHighlyComposite.aspx">Highly Composite Numbers</a>.
%F A140645 a(n) = A007953(A002182(n)). - _Amiram Eldar_, Nov 13 2019
%e A140645 2162160 is a highly composite number whose digit sum is 18.
%t A140645 HCN=NestList[Function[last,Module[{d = DivisorSigma[0, last]},NestWhile[# + 1 &, last, DivisorSigma[0, #] <= d &]]], 1,40]; DigitSum/@HCN (* _James C. McMahon_, Jul 12 2025 *)
%Y A140645 Cf. A002182, A002183, A007953, A117825, A127390.
%K A140645 nonn,base
%O A140645 1,2
%A A140645 _Parthasarathy Nambi_, Jul 08 2008