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A202388 Digital root of Smith numbers A006753. 4
4, 4, 9, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 9, 4, 4, 6, 4, 6, 4, 4, 4, 4, 9, 3, 6, 4, 6, 6, 9, 6, 6, 9, 6, 4, 8, 9, 6, 4, 6, 6, 6, 4, 4, 6, 4, 4, 4, 6, 4, 4, 4, 4, 4, 6, 8, 9, 4, 6, 6, 4, 4, 4, 8, 9, 3, 4, 4, 6, 4, 9, 9, 4, 4, 9, 4, 9, 8, 9, 4, 4, 6, 9, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = A010888(A006753(n)); range = {4,6,8,9}.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Smith Number

Wikipedia, Smith number

MATHEMATICA

d[n_]:=IntegerDigits[n]; dr[n_]:= NestWhile[Total[d[#]]&, n, #>9&]; tr[n_]:=Transpose[FactorInteger[n]]; t1=Select[Range[4, 2.2*10^3], !PrimeQ[#]&&Total[d[#]]==Total[d@tr[#][[1]]*tr[#][[2]], 2]&]; Table[dr[n], {n, t1}] (* t1 gives Smith numbers - Jayanta Basu, Jun 04 2013 *)

CROSSREFS

Cf. A050218, A202393.

Sequence in context: A272427 A068340 A097667 * A283919 A283670 A019627

Adjacent sequences:  A202385 A202386 A202387 * A202389 A202390 A202391

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller, Dec 19 2011

STATUS

approved

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Last modified December 12 12:50 EST 2019. Contains 329958 sequences. (Running on oeis4.)