%I #20 May 27 2024 02:40:32
%S 0,0,1,2,4,5,7,7,9,10,12,12,15,15,16,18,20,20,22,22,25,26,27,27,30,31,
%T 32,33,35,35,38,38,40,41,42,43,46,46,47,48,51,51,53,53,55,57,58,58,61,
%U 61,63,64,66,66,68,69,71,72,73,73,77,77,78,79,81,82,84,84,86,87
%N a(n) = floor(n/2) + floor(n/3) + floor(n/4) + floor(n/5).
%H Vincenzo Librandi, <a href="/A187325/b187325.txt">Table of n, a(n) for n = 0..10000</a>
%F a(n) = floor(n/2) + floor(n/3) + floor(n/4) + floor(n/5).
%F a(n) = -a(n-1) - a(n-2) + a(n-4) + 2*a(n-5) + 2*a(n-6) + a(n-7) - a(n-9) - a(n-10) - a(n-11).
%F G.f.: x^2*(2*x^4 + 3*x^3 + 3*x^2 + 2*x + 1)*(2*x^4 + x^3 + 2*x^2 + x + 1) / ( (1+x)*(1 + x + x^2)*(x^4 + x^3 + x^2 + x + 1)*(x^2+1)*(x-1)^2 ). - _R. J. Mathar_, Mar 08 2011
%t Table[Floor[n/2]+Floor[n/3]+Floor[n/4]+Floor[n/5], {n,0,120}]
%t Table[Total[Floor[n/Range[2,5]]],{n,0,120}] (* _Harvey P. Dale_, Nov 22 2015 *)
%o (Magma) [Floor(n/2)+Floor(n/3)+Floor(n/4)+Floor(n/5): n in [0..130] ]; // _Vincenzo Librandi_, Jul 18 2011
%K nonn
%O 0,4
%A _Clark Kimberling_, Mar 08 2011