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*(45601 + 109598*x + 4801*x^2)/(1-x)^3.
E.g.f.: (4801 + 40800*x + 80000*x^2)*exp(x) - 4801. - G. C. Greubel, Nov 17 2018
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {45601, 246401, 607201}, 40]
PROG
(Magma) I:=[45601, 246401, 607201]; [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 - 39200*n + 4801.
(Sage) [80000*n^2-39200*n+4801 for n in (1..40)] # G. C. Greubel, Nov 17 2018
(GAP) List([1..40], n -> 80000*n^2-39200*n+4801); # G. C. Greubel, Nov 17 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 03 2009
STATUS
approved