OFFSET
1,1
COMMENTS
The identity (103680000*n^2 - 28800*n + 1)^2 - (3600*n^2 - n)*(1728000*n - 240)^2 = 1 can be written as A157859(n)^2 - a(n)*A157858(n)^2 = 1 (see second comment at A157858). - Vincenzo Librandi, Jan 25 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 (3,-3,1).
FORMULA
G.f.: x*(3599 + 3601*x)/(1-x)^3. - Colin Barker, Jan 17 2012
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Vincenzo Librandi, Jan 25 2012
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {3599, 14398, 32397}, 40] (* Vincenzo Librandi, Jan 25 2012 *)
Table[3600n^2-n, {n, 30}] (* Harvey P. Dale, Apr 13 2019 *)
PROG
(Magma) I:=[3599, 14398, 32397]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Jan 25 2012
(PARI) for(n=1, 30, print1(3600*n^2 - n", ")); \\ Vincenzo Librandi, Jan 25 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 08 2009
STATUS
approved