A187321 - OEIS

%I #21 Jan 31 2023 15:41:27

%S 0,0,1,1,3,3,4,4,6,6,7,7,9,9,10,10,12,12,13,13,15,15,16,16,18,18,19,

%T 19,21,21,22,22,24,24,25,25,27,27,28,28,30,30,31,31,33,33,34,34,36,36,

%U 37,37,39,39,40,40,42,42,43,43,45,45,46,46,48,48,49,49,51,51,52,52,54

%N a(n) = floor(n/2) + floor(n/4).

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1)

%F a(n) = floor(n/2) + floor(n/4).

%F G.f.: x^2*(1+2*x^2)/((1+x)*(x^2+1)*(x-1)^2). - _R. J. Mathar_, Mar 08 2011

%F a(n) = A032766(floor(n/2)). - _Bruno Berselli_, Mar 08 2011

%F a(n) = (6*n-5+2*cos(n*Pi/2)+3*cos(n*Pi)+2*sin(n*Pi/2))/8. - _Wesley Ivan Hurt_, Oct 02 2017

%F a(n) = A004526(n) + A002265(n). - _Michel Marcus_, Jan 31 2023

%t Table[Floor[n/2]+Floor[n/4], {n,0,120}]

%o (Python)

%o def A187321(n): return 3*(n>>2)+bool(n&2) # _Chai Wah Wu_, Jan 31 2023

%Y Cf. A032766, A004526, A002265.

%K nonn,easy

%O 0,5

%A _Clark Kimberling_, Mar 08 2011