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%I #26 Mar 04 2024 01:12:50
%S 1,10,10,19,19,28,28,37,37,46,46,55,55,64,64,73,73,82,82,91,91,100,
%T 100,109,109,118,118,127,127,136,136,145,145,154,154,163,163,172,172,
%U 181,181,190,190,199,199,208,208,217,217,226,226,235,235,244,244,253,253
%N a(n) = 1 + 9*floor(n/2).
%H Vincenzo Librandi, <a href="/A168416/b168416.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F a(n) = 9*n - a(n-1) - 7, with n>1, a(1)=1.
%F G.f.: x*(1 + 9*x - x^2)/((1+x)*(x-1)^2). - _Vincenzo Librandi_, Sep 19 2013
%F a(n) = a(n-1) +a(n-2) -a(n-3). - _Vincenzo Librandi_, Sep 19 2013
%F E.g.f.: (1/4)*(9 - 4*exp(x) + (18*x - 5)*exp(2*x))*exp(-x). - _G. C. Greubel_, Jul 22 2016
%t Table[1 + 9 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[(1 + 9 x - x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* _Vincenzo Librandi_, Sep 19 2013 *)
%o (Magma) [1+9*Floor(n/2): n in [1..70]]; // _Vincenzo Librandi_, Sep 19 2013
%Y Cf. A017173.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Nov 25 2009
%E New definition by _Vincenzo Librandi_, Sep 19 2013
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