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a(n) = 4*n^3 - 6*n^2 + 1.
9

%I #41 Mar 12 2024 02:32:49

%S 1,-1,9,55,161,351,649,1079,1665,2431,3401,4599,6049,7775,9801,12151,

%T 14849,17919,21385,25271,29601,34399,39689,45495,51841,58751,66249,

%U 74359,83105,92511,102601,113399,124929,137215,150281,164151,178849,194399,210825,228151

%N a(n) = 4*n^3 - 6*n^2 + 1.

%H G. C. Greubel, <a href="/A141530/b141530.txt">Table of n, a(n) for n = 0..500</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).

%F a(n) = (2*n-1)*(2*n^2 - 2*n - 1) = A060747(n)*A132209(n-1), n > 1. - _R. J. Mathar_, Feb 22 2009

%F G.f.: (1 - 5*x + 19*x^2 + 9*x^3)/(1-x)^4. - _Jaume Oliver Lafont_, Aug 30 2009

%F a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) with a(0)=1, a(1)=-1, a(2)=9, a(3)=55. - _Harvey P. Dale_, Nov 30 2011

%F E.g.f.: (1 - 2*x + 6*x^2 + 4*x^3)*exp(x). - _G. C. Greubel_, Mar 29 2021

%p A141530:= n-> 4*n^3 -6*n^2 +1; seq(A141530(n), n=0..50); # _G. C. Greubel_, Mar 29 2021

%t Array[4*#^3-6*#^2+1&,50,0] (* _Vladimir Joseph Stephan Orlovsky_, Nov 03 2009 *)

%t LinearRecurrence[{4,-6,4,-1},{1,-1,9,55},50] (* _Harvey P. Dale_, Nov 30 2011 *)

%o (PARI) a(n)=4*n^3-6*n^2+1 \\ _Charles R Greathouse IV_, Oct 07 2015

%o (Magma) [4*n^3 -6*n^2 +1: n in [0..50]]; // _G. C. Greubel_, Mar 29 2021

%o (Sage) [4*n^3 -6*n^2 +1 for n in (0..50)] # _G. C. Greubel_, Mar 29 2021

%o (Python)

%o def A141530(n): return (m:=(n<<1)-1)*(n*(m-1)-1) # _Chai Wah Wu_, Mar 11 2024

%Y Cf. A046092, A141047, A141417.

%Y See Librandi's comment in A078371.

%K sign,less,easy

%O 0,3

%A _Paul Curtz_, Aug 12 2008

%E Corrected, completed and edited, following an observation from _Vincenzo Librandi_, by _M. F. Hasler_, Feb 12 2009

%E Further edited by _N. J. A. Sloane_, Feb 13 2009