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%I #12 Jun 13 2023 08:42:21
%S 0,0,0,0,1,3,6,10,16,25,36,49,66,85,109,136,168,204,244,290,342,399,
%T 462,531,607,690,780,877,982,1096,1218,1348,1488,1636,1795,1963,2142,
%U 2331,2530,2741,2964,3198,3444
%N [ n(n-1)(n-2)/20 ].
%H <a href="/index/Rec#order_23">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -3, 3, -1).
%F a(n) = +3*a(n-1) -3*a(n-2) +a(n-3) +a(n-20) -3*a(n-21) +3*a(n-22) -a(n-23). G.f.: x^4*(1+x^4+x^5-x^6+2*x^8-2*x^9+3*x^10-2*x^11+2*x^12-x^13+2*x^15-x^17+x^18) / ( (-1+x)^4*(1+x^4+x^3+x^2+x)*(1+x)*(1-x+x^2-x^3+x^4)*(1+x^2)*(x^8-x^6+x^4-x^2+1) ). [From _R. J. Mathar_, Apr 15 2010]
%t Table[Floor[(n(n-1)(n-2))/20],{n,0,80}] (* _Harvey P. Dale_, Mar 23 2011 *)
%K nonn
%O 0,6
%A _N. J. A. Sloane_.
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