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A187326 a(n) = floor(n/4) + floor(n/2) + floor(3n/4).

%I A187326 #54 May 27 2024 12:27:14
%S A187326 0,0,2,3,6,6,8,9,12,12,14,15,18,18,20,21,24,24,26,27,30,30,32,33,36,
%T A187326 36,38,39,42,42,44,45,48,48,50,51,54,54,56,57,60,60,62,63,66,66,68,69,
%U A187326 72,72,74,75,78,78,80,81,84,84,86,87,90,90,92,93,96,96,98,99,102,102,104,105,108,108,110,111,114,114,116,117
%N A187326 a(n) = floor(n/4) + floor(n/2) + floor(3n/4).
%H A187326 Vincenzo Librandi, <a href="/A187326/b187326.txt">Table of n, a(n) for n = 0..10000</a>
%H A187326 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A187326 G.f.: x^2*(2+x+3*x^2) / ( (1+x)*(x^2+1)*(x-1)^2 ). - _R. J. Mathar_, Mar 08 2011
%F A187326 a(n) = +1*a(n-1) +1*a(n-4) -1*a(n-5). - _Joerg Arndt_, Apr 01 2011
%F A187326 a(n) = (6*(n-1)+(1+(-1)^n)*(2+i^n))/4, where i=sqrt(-1). - _Bruno Berselli_, Mar 08 2011
%F A187326 a(n) = (3*n-4+gcd(4,n))/2. - _Jose Eduardo Blazek_, Mar 22 2014
%F A187326 a(n+1) = a(n)+(3+gcd(4,n+1)-gcd(4,n))/2 and a(0)=0. - _Jose Eduardo Blazek_, Mar 23 2014
%F A187326 a(n+4) = a(n) + 6. - _Michael Somos_, Feb 23 2014
%e A187326 G.f. = 2*x^2 + 3*x^3 + 6*x^4 + 6*x^5 + 8*x^6 + 9*x^7 + 12*x^8 + 12*x^9 + ...
%t A187326 Table[Floor[n/4]+Floor[n/2]+Floor[3n/4], {n,0,120}]
%t A187326 LinearRecurrence[{1,0,0,1,-1},{0,0,2,3,6},100] (* _Harvey P. Dale_, May 27 2016 *)
%o A187326 (Magma) [Floor(n/4)+Floor(n/2)+Floor(3*n/4): n in [0..90] ]; // _Vincenzo Librandi_, Jul 18 2011
%o A187326 (PARI) {a(n) = (3*n - n%2) / 2 - (n%4!=0)}; /* _Michael Somos_, Feb 23 2014 */
%o A187326 (PARI) a(n)=n\4 + n\2 + 3*n\4 \\ _Charles R Greathouse IV_, Jul 19 2016
%Y A187326 Cf. A187333.
%K A187326 nonn,easy
%O A187326 0,3
%A A187326 _Clark Kimberling_, Mar 08 2011