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%I A128990 #22 Sep 08 2022 08:45:30
%S A128990 0,196,6174,115248,1680700,21176820,242121642,2582630848,26149137336,
%T A128990 254227724100,2392565359030,21924598926384,196490913105396,
%U A128990 1728112389619252,14954818756320450,127614453387267840
%N A128990 a(n) = (n^3 - n^2)*7^n.
%H A128990 Vincenzo Librandi, <a href="/A128990/b128990.txt">Table of n, a(n) for n = 1..1000</a>
%H A128990 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (28, -294, 1372, -2401).
%F A128990 G.f.: 98*x^2*(2+7*x)/(1-7*x)^4. - _Vincenzo Librandi_, Feb 12 2013
%F A128990 a(n) = 28*a(n-1)-294*a(n-2)+1372*a(n-3)-2401*a(n-4). - _Vincenzo Librandi_, Feb 12 2013
%t A128990 CoefficientList[Series[98 x (2 + 7 x)/(1 - 7 x)^4, {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 12 2013 *)
%t A128990 LinearRecurrence[{28,-294,1372,-2401},{0,196,6174,115248},20] (* _Harvey P. Dale_, Mar 04 2015 *)
%o A128990 (Magma) [(n^3-n^2)*7^n: n in [1..25]]; /* or */ I:=[0,196,6174,115248]; [n le 4 select I[n] else 28*Self(n-1)-294*Self(n-2)+1372*Self(n-3)-2401*Self(n-4): n in [1..25]]; // _Vincenzo Librandi_, Feb 12 2013
%Y A128990 Cf. A128796, A036289.
%K A128990 nonn,easy
%O A128990 1,2
%A A128990 _Mohammad K. Azarian_, Apr 30 2007
%E A128990 Offset corrected by _Mohammad K. Azarian_, Nov 20 2008

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