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 A011907 [ n(n-1)(n-2)/25 ]. 0

%I

%S 0,0,0,0,0,2,4,8,13,20,28,39,52,68,87,109,134,163,195,232,273,319,369,

%T 425,485,552,624,702,786,876,974,1078,1190,1309,1436,1570,1713,1864,

%U 2024,2193,2371,2558,2755,2961

%N [ n(n-1)(n-2)/25 ].

%H <a href="/index/Rec#order_28">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, 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-25) -3*a(n-26) +3*a(n-27) -a(n-28). G.f.: x^5*(2-2*x+2*x^2-x^3+x^4-x^5+2*x^6-x^7+x^8+x^12-x^13+2*x^14-x^15+x^16-x^17+2*x^18-2*x^19+3*x^20-2*x^21+x^22) / ( (-1+x)^4*(1+x^4+x^3+x^2+x)*(x^20+x^15+x^10+x^5+1) ). [From _R. J. Mathar_, Apr 15 2010]

%t Table[Floor[(n(n-1)(n-2))/25],{n,0,60}] (* or *) LinearRecurrence[{3,-3,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,-3,3,-1},{0,0,0,0,0,2,4,8,13,20,28,39,52,68,87,109,134,163,195,232,273,319,369,425,485,552,624,702},60] (* _Harvey P. Dale_, Aug 25 2021 *)

%K nonn

%O 0,6

%A _N. J. A. Sloane_.

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Last modified December 2 17:59 EST 2021. Contains 349445 sequences. (Running on oeis4.)