OFFSET
1,1
COMMENTS
The identity (10368*n^2-15840*n+6049)^2-(36*n^2-55*n+21)*(1728*n-1320)^2=1 can be written as A157264(n)^2-A157262(n)*a(n)^2=1. - Vincenzo Librandi, Jan 27 2012
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). - Vincenzo Librandi, Jan 27 2012
G.f.: x*(408+1320*x)/(x-1)^2. - Vincenzo Librandi, Jan 27 2012
E.g.f.: (1728*x - 1320)*exp(x) + 1320. - G. C. Greubel, Feb 04 2018
MATHEMATICA
LinearRecurrence[{2, -1}, {408, 2136}, 40] (* Vincenzo Librandi, Jan 27 2012 *)
1728*Range[40]-1320 (* Harvey P. Dale, Aug 09 2012 *)
PROG
(Magma) I:=[408, 2136]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Jan 27 2012
(PARI) for(n=1, 40, print1(1728*n - 1320", ")); \\ Vincenzo Librandi, Jan 27 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 26 2009
STATUS
approved