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Digital root of 3n.
7

%I #42 Nov 26 2022 07:48:49

%S 0,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,

%T 3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,

%U 6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6,9,3,6

%N Digital root of 3n.

%C Decimal expansion of 41/1110. - _Enrique Pérez Herrero_, Nov 13 2021

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1).

%F a(n+1) = 3*A010882(n). - _Reinhard Zumkeller_, Oct 25 2010

%F G.f.: (-3*(1 + 2*x + 3*x^2))/(-1 + x^3) for n>0. - _Alexander R. Povolotsky_, Jun 13 2012

%F a(n) = A010888(A002277(n)). - _Enrique Pérez Herrero_, Nov 24 2022

%F a(n) = A010888(A008585(n)). - _Michel Marcus_, Nov 24 2022

%t digitalRoot[n_Integer?Positive] := FixedPoint[Plus@@IntegerDigits[#]&,n]; Table[If[n==0,0,digitalRoot[3*n]], {n,0,200}] (* _Vladimir Joseph Stephan Orlovsky_, May 02 2011 *)

%t LinearRecurrence[{0,0,1},{0,3,6,9},120] (* _Harvey P. Dale_, Sep 03 2020 *)

%Y Cf. A008585 (3*n), A010888 (digital root), A002277.

%Y Cf. A180592, A180594, A180595, A180596, A180597, A180598, A180599.

%K nonn,base,easy

%O 0,2

%A _Odimar Fabeny_, Sep 10 2010

%E Edited by _N. J. A. Sloane_, Sep 23 2010