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*(-1107-9737*x-2278*x^2)/(x-1)^3.
E.g.f.: (6561*x^2 - 1171*x + 2278)*exp(x) - 2278. - G. C. Greubel, Feb 04 2018
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {1107, 13058, 38131}, 40]
Table[6561*n^2-7732*n+2278, {n, 1, 30}] (* G. C. Greubel, Feb 04 2018 *)
PROG
(Magma) I:=[1107, 13058, 38131]; [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) = 6561*n^2 - 7732*n + 2278.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 28 2009
STATUS
approved