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A162699 Odd numbers not divisible by 7. 7

%I

%S 1,3,5,9,11,13,15,17,19,23,25,27,29,31,33,37,39,41,43,45,47,51,53,55,

%T 57,59,61,65,67,69,71,73,75,79,81,83,85,87,89,93,95,97,99,101,103,107,

%U 109,111,113,115,117,121,123,125,127,129,131,135,137,139,141,143,145,149

%N Odd numbers not divisible by 7.

%C Numbers coprime to 14. The asymptotic density of this sequence is 3/7. - _Amiram Eldar_, Oct 18 2020

%H Amiram Eldar, <a href="/A162699/b162699.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,1,-1).

%F a(n) = 2*n + 1 + 2*floor( (2*n-7)/12 ).

%F a(n) = a(n-1)+a(n-6)-a(n-7). G.f.: x*(x^2+1)*(x^4+2*x^3+x^2+2*x+1)/ ((1+x)*(1+x+x^2)*(x^2-x+1)*(x-1)^2). - _R. J. Mathar_, Jul 31 2009

%t s={}; Do[If[Mod[n, 7] > 0, AppendTo[s, n]], {n, 1, 60, 2}]; s

%t Table[2 n + 1 + 2*Floor[(2 n - 7)/12], {n, 1, 99}]

%t DeleteCases[Range[1,151,2],_?(Divisible[#,7]&)] (* _Harvey P. Dale_, Jul 04 2015 *)

%o (PARI) a(n)=(14*n-7)\12*2+1 \\ _Charles R Greathouse IV_, Jun 11 2015

%Y Cf. A045572 (odd numbers not divisible by 5).

%K nonn,easy

%O 1,2

%A _Zak Seidov_, Jul 11 2009

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Last modified April 20 08:38 EDT 2021. Contains 343125 sequences. (Running on oeis4.)