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a(n) = floor(n^3/9).
2

%I #16 Mar 18 2024 09:47:46

%S 0,0,0,3,7,13,24,38,56,81,111,147,192,244,304,375,455,545,648,762,888,

%T 1029,1183,1351,1536,1736,1952,2187,2439,2709,3000,3310,3640,3993,

%U 4367,4763,5184,5628,6096,6591,7111,7657,8232,8834,9464,10125,10815,11535

%N a(n) = floor(n^3/9).

%H Harry J. Smith, <a href="/A061263/b061263.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,2,-3,3,-1).

%F G.f.: x^3*(3-2*x+x^2) / ( (1+x+x^2)*(x-1)^4 ). - _R. J. Mathar_, Feb 20 2011

%e a(4) = floor(4^3 / 9) = floor(64/9) = 7.

%o (PARI) { for (n=0, 1000, write("b061263.txt", n, " ", n^3\9) ) } \\ _Harry J. Smith_, Jul 20 2009

%Y Cf. A061105.

%K easy,nonn

%O 0,4

%A _Henry Bottomley_, Apr 24 2001