Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #17 Nov 05 2024 09:32:02
%S 0,0,2,4,16,24,54,72,128,160,250,300,432,504,686,784,1024,1152,1458,
%T 1620,2000,2200,2662,2904,3456,3744,4394,4732,5488,5880,6750,7200,
%U 8192,8704,9826,10404,11664,12312,13718,14440,16000,16800
%N a(n) = floor(n/2) * floor(n^2/2).
%H Vincenzo Librandi, <a href="/A131475/b131475.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1, 3, -3, -3, 3, 1, -1).
%F G.f.: 2*x^2*(1 + x + 3*x^2 + x^3)/((1+x)^3*(1-x)^4). - _R. J. Mathar_, Dec 19 2008
%F a(n) = a(n-1) + 3*a(n-2) - 3*a(n-3) - 3*a(n-4) + 3*a(n-5) + a(n-6) - a(n-7).
%F a(n) = A004526(n)*A007590(n). - _R. J. Mathar_, Mar 04 2018
%o (Magma) [Floor(n/2)*Floor(n^2/2): n in [0..60]]; // _Vincenzo Librandi_, Jun 16 2011
%Y Cf. A000982, A008619, A004526, A007590.
%K nonn,easy
%O 0,3
%A _Mohammad K. Azarian_, Jul 27 2007