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 A161184 #13 Feb 21 2019 02:53:40
%S A161184 1,2,4,6,3,6,9,3,6,3,9,6,9,9,3,9,6,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
%T A161184 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
%U A161184 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9
%N A161184 Digital roots of highly composite numbers (A002182).
%C A161184 a(n)=9 for n > 17 because for those n, the highly composite number A002182(n) is divisible by 9. - _T. D. Noe_, Jul 28 2009
%F A161184 a(n) = A010888(A140645(n)). - _R. J. Mathar_, Jun 15 2009
%e A161184 7560 is a highly composite number whose digital root is 9.
%p A161184 read("transforms3"): L := BFILETOLIST("b002182.txt") : A007953 := proc(n) add(d,d=convert(n,base,10)) ; end: A010888 := proc(n) local a ; a := A007953(n) ; while a > 9 do a := A007953(a) ; od; a; end: for i from 1 to 200 do printf("%d,", A010888(op(i,L))) ; od: # _R. J. Mathar_, Jun 15 2009
%Y A161184 Cf. A002182, A010888, A140645.
%K A161184 nonn,easy,base
%O A161184 1,2
%A A161184 _Parthasarathy Nambi_, Jun 05 2009
%E A161184 Extended by _R. J. Mathar_, Jun 15 2009