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*(-27227-27223*x)/(x-1)^3.
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {27227, 108904, 245031}, 30]
PROG
(Magma) I:=[27227, 108904, 245031]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+Self(n-3): n in [1..30]];
(PARI) a(n) = 27225*n^2 + 2*n.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 07 2009
EXTENSIONS
Corrected by Charles R Greathouse IV, Aug 09 2010
STATUS
approved