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A161184 Digital roots of highly composite numbers (A002182). 1
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, 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, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..87.

FORMULA

a(n) = A010888(A140645(n)). - R. J. Mathar, Jun 15 2009

EXAMPLE

7560 is a highly composite number whose digital root is 9.

MAPLE

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

CROSSREFS

Cf. A002182, A010888, A140645.

Sequence in context: A075075 A088178 A259840 * A140645 A327724 A117532

Adjacent sequences:  A161181 A161182 A161183 * A161185 A161186 A161187

KEYWORD

nonn,easy,base

AUTHOR

Parthasarathy Nambi, Jun 05 2009

EXTENSIONS

Extended by R. J. Mathar, Jun 15 2009

STATUS

approved

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Last modified February 26 11:49 EST 2020. Contains 332279 sequences. (Running on oeis4.)