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%I #23 Mar 03 2022 13:05:32
%S 0,0,0,1,2,3,5,7,9,11,14,17,20,24,28,32,36,41,46,51,57,63,69,75,82,89,
%T 96,104,112,120,128,137,146,155,165,175,185,195,206,217,228,240,252,
%U 264,276,289,302,315,329,343,357,371,386,401,416,432,448
%N a(n) = floor(n^2/7).
%H Vincenzo Librandi, <a href="/A056834/b056834.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,1,-2,1).
%F a(n) = +2*a(n-1) -a(n-2) +a(n-7) -2*a(n-8) +a(n-9).
%F G.f.: -x^3*(1+x)*(x^2-x+1) / ( (x^6+x^5+x^4+x^3+x^2+x+1)*(x-1)^3 ).
%t Floor[(Range[0,60]^2)/7] (* or *) LinearRecurrence[{2,-1,0,0,0,0,1,-2,1},{0,0,0,1,2,3,5,7,9},60] (* _Harvey P. Dale_, Jul 21 2014 *)
%t CoefficientList[Series[-x^3 (1 + x) (x^2 - x + 1)/((x^6 + x^5 + x^4 + x^3 + x^2 + x + 1) (x - 1)^3), {x, 0, 100}], x] (* _Vincenzo Librandi_, Jul 22 2014 *)
%o (PARI) a(n) = n^2\7; \\ _Michel Marcus_, Mar 03 2022
%Y Cf. A000290, A007590, A000212, A002620, A118015, A056827, A130519, A056838, A056865.
%K nonn,easy
%O 0,5
%A _N. J. A. Sloane_, Sep 02 2000
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