A064806 - OEIS

%I #29 Dec 28 2024 11:50:36

%S 2,4,6,8,10,12,14,16,18,11,13,15,17,19,21,23,25,27,20,22,24,26,28,30,

%T 32,34,36,29,31,33,35,37,39,41,43,45,38,40,42,44,46,48,50,52,54,47,49,

%U 51,53,55,57,59,61,63,56,58,60,62,64,66,68,70,72,65,67,69,71

%N a(n) = n + digital root of n.

%H Harry J. Smith, <a href="/A064806/b064806.txt">Table of n, a(n) for n=1..1000</a>

%H <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,1,-1).

%H <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>

%F a(n) = n + A010888(n).

%F G.f.: -x*(9*x^9-2*x^8-2*x^7-2*x^6-2*x^5-2*x^4-2*x^3-2*x^2-2*x-2) / ((x-1)^2*(x^2+x+1)*(x^6+x^3+1)). - _Colin Barker_, Apr 05 2013

%p A064806 := proc(n) return n+1 + ((n-1) mod 9): end: seq(A064806(n), n=1..100); # _Nathaniel Johnston_, May 04 2011

%t Table[n+Mod[n-1,9]+1,{n,70}] (* or *) LinearRecurrence[{1,0,0,0,0,0,0,0,1,-1},{2,4,6,8,10,12,14,16,18,11},70] (* _Harvey P. Dale_, Nov 19 2022 *)

%o (PARI) a(n) = { n + (n - 1)%9 + 1 } \\ _Harry J. Smith_, Sep 26 2009

%o (Haskell)

%o a064806 n = n + a010888 n  -- _Reinhard Zumkeller_, Apr 13 2013

%Y Cf. A010888 (digital root of n), A062028 (sum of digits of n).

%K nonn,easy,base

%O 1,1

%A _Reinhard Zumkeller_, Oct 21 2001