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
G.f: x*(70+273*x)/(1-x)^2.
E.g.f.: 7*(39 - (39-49*x)*exp(x)). - G. C. Greubel, Feb 02 2018
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {70, 413, 756}, 40]
343Range[40]-273 (* Harvey P. Dale, Mar 13 2011 *)
PROG
(Magma) I:=[70, 413, 756]; [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)= 343*n-273.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 28 2009
STATUS
approved