A161184 Digital roots of highly composite numbers (A002182).

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

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 * A349543 A140645 A327724

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