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%I #13 Feb 21 2019 02:53:40
%S 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 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 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9
%N Digital roots of highly composite numbers (A002182).
%C 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 a(n) = A010888(A140645(n)). - _R. J. Mathar_, Jun 15 2009
%e 7560 is a highly composite number whose digital root is 9.
%p 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 Cf. A002182, A010888, A140645.
%K nonn,easy,base
%O 1,2
%A _Parthasarathy Nambi_, Jun 05 2009
%E Extended by _R. J. Mathar_, Jun 15 2009
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