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%I #25 Mar 04 2024 01:13:20
%S 4,14,14,24,24,34,34,44,44,54,54,64,64,74,74,84,84,94,94,104,104,114,
%T 114,124,124,134,134,144,144,154,154,164,164,174,174,184,184,194,194,
%U 204,204,214,214,224,224,234,234,244,244,254,254,264,264,274,274,284
%N a(n) = 4 + 10*floor(n/2).
%H Vincenzo Librandi, <a href="/A168420/b168420.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) = 10*n - a(n-1) - 2, with n>1, a(1)=4.
%F G.f.: 2*x*(2 + 5*x - 2*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 a(n) = 2*A168278(n). - _Bruno Berselli_, Sep 19 2013
%F E.g.f.: (1/2)*(5 - 8*exp(x) + (10*x + 3)*exp(2*x))*exp(-x). - _G. C. Greubel_, Jul 22 2016
%t Table[4 + 10 Floor[n/2], {n, 70}] (* or *) CoefficientList[Series[(4 + 10 x - 4 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* _Vincenzo Librandi_, Sep 19 2013 *)
%o (Magma) [4+10*Floor(n/2): n in [1..70]]; // _Vincenzo Librandi_, Sep 19 2013
%Y Cf. A017317, A168278.
%K nonn,easy,less
%O 1,1
%A _Vincenzo Librandi_, Nov 25 2009
%E New definition by _Vincenzo Librandi_, Sep 19 2013
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