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 (2,-1).
FORMULA
a(n) = 2*a(n-1) - a(n-2).
G.f.: x*(1960+6040*x)/(x-1)^2.
MATHEMATICA
LinearRecurrence[{2, -1}, {1960, 9960}, 40]
PROG
(Magma) I:=[1960, 9960]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]];
(PARI) a(n)=8000*n-6040 \\ Charles R Greathouse IV, Dec 27 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 03 2009
STATUS
approved