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%I #30 Sep 08 2022 08:44:52
%S 0,1,1,2,2,4,5,7,8,11,13,16,18,22,25,29,32,37,41,46,50,56,61,67,72,79,
%T 85,92,98,106,113,121,128,137,145,154,162,172,181,191,200,211,221,232,
%U 242,254,265,277,288,301,313,326,338,352,365,379,392
%N a(n) = ceiling(n^2/8).
%H Vincenzo Librandi, <a href="/A036406/b036406.txt">Table of n, a(n) for n = 0..10000</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,1,-2,1)
%F a(n) = (1/16)*(2n^2 + 9 - 5(-1)^n - 2(-1)^floor(n/2) + 2(-1)^floor((n-1)/2)). - _Ralf Stephan_, Jun 10 2005
%F G.f.: -x*(1-x-x^3+x^2+x^4) / ( (1+x)*(1+x^2)*(x-1)^3 ). - _R. J. Mathar_, Jan 22 2011
%F a(n) = 2*a(n-1) - a(n-2) + a(n-4) - 2*a(n-5) + a(n-6); a(0)=0, a(1)=1, a(2)=1, a(3)=2, a(4)=2, a(5)=4. - _Harvey P. Dale_, Jun 21 2011
%p A036406:=n->ceil(n^2/8); seq(A036406(n), n=0..60); # _Wesley Ivan Hurt_, Feb 14 2014
%t Ceiling[Range[0,60]^2/8] (* or *) LinearRecurrence[{2,-1,0,1,-2,1},{0,1,1,2,2,4},60] (* _Harvey P. Dale_, Jun 21 2011 *)
%o (Magma) [Ceiling(n^2/8):n in [0..60]]; // _Vincenzo Librandi_, Oct 21 2011
%o (PARI) a(n)=ceil(n^2/8) \\ _Charles R Greathouse IV_, Feb 14 2014
%K nonn,easy
%O 0,4
%A _N. J. A. Sloane_
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