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A156774 6561n^2 - 3564n + 485. 3

%I

%S 485,3482,19601,48842,91205,146690,215297,297026,391877,499850,620945,

%T 755162,902501,1062962,1236545,1423250,1623077,1836026,2062097,

%U 2301290,2553605,2819042,3097601,3389282,3694085,4012010,4343057,4687226

%N 6561n^2 - 3564n + 485.

%C The identity (6561*n^2-3564*n+485)^2-(81*n^2-44*n+6)*(729*n-198)^2=1 can be written as a(n)^2-A156676(n)* A156772(n)^2=1 for n>0.

%H Vincenzo Librandi, <a href="/A156774/b156774.txt">Table of n, a(n) for n = 0..10000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

%F a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).

%F G.f.: (-485-2027*x-10610*x^2)/(x-1)^3.

%t LinearRecurrence[{3,-3,1},{485,3482,19601},40]

%o (MAGMA) I:=[485, 3482, 19601]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];

%o (PARI) a(n)= 6561*n^2-3564*n+485 \\ _Charles R Greathouse IV_, Dec 23 2011

%Y Cf. A156676, A156772.

%K nonn,easy

%O 0,1

%A _Vincenzo Librandi_, Feb 15 2009

%E Edited by _Charles R Greathouse IV_, Jul 25 2010

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Last modified July 15 23:32 EDT 2020. Contains 335774 sequences. (Running on oeis4.)