OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Vincenzo Librandi, X^2-AY^2=1
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
G.f.: x*(-4801-109598*x-45601*x^2)/(x-1)^3.
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {4801, 124001, 403201}, 40]
Rest[CoefficientList[Series[x (-4801-109598x-45601x^2)/(x-1)^3, {x, 0, 30}], x]] (* Harvey P. Dale, Apr 30 2022 *)
PROG
(Magma) I:=[4801, 124001, 403201]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
(PARI) a(n)=80000*n^2-120800*n+45601 \\ Charles R Greathouse IV, Dec 27 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 03 2009
STATUS
approved