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a(n) = floor(n^2/10).
13

%I #19 Jun 29 2022 14:46:15

%S 0,0,0,0,1,2,3,4,6,8,10,12,14,16,19,22,25,28,32,36,40,44,48,52,57,62,

%T 67,72,78,84,90,96,102,108,115,122,129,136,144,152,160,168,176,184,

%U 193,202,211,220,230,240,250,260,270,280,291,302,313,324

%N a(n) = floor(n^2/10).

%H <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,0,1,-2,1).

%F G.f.: -x^4*(1+x^4) / ( (1+x)*(x^4-x^3+x^2-x+1)*(x^4+x^3+x^2+x+1)*(x-1)^3 ). - _R. J. Mathar_, Mar 08 2016

%p A056865 := proc(n)

%p floor(n^2/10) ;

%p end proc:

%p seq(A056865(n),n=0..100) ; # _R. J. Mathar_, Mar 08 2016

%t Floor[Range[0,60]^2/10] (* or *) LinearRecurrence[{2,-1,0,0,0,0,0,0,0,1,-2,1},{0,0,0,0,1,2,3,4,6,8,10,12},60] (* _Harvey P. Dale_, Jun 29 2022 *)

%o (PARI) a(n) = n^2\10; \\ _Michel Marcus_, Mar 08 2016

%Y Cf. A056864.

%Y Cf. A000290, A007590, A000212, A002620, A118015, A056827, A056834, A130519, A056838.

%K nonn,easy

%O 0,6

%A _N. J. A. Sloane_, Sep 02 2000