OFFSET
1,1
COMMENTS
The identity (13122*n^2 + 324*n + 1)^2 - (81*n^2 + 2*n)*(1458*n + 18)^2 = 1 can be written as A157506(n)^2 - A177099(n)*a(n)^2 = 1 (see Bruno Berselli's comment at A177099). - Vincenzo Librandi, Feb 04 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
G.f.: x*(1476 - 18*x)/(1-x)^2. - Vincenzo Librandi, Feb 04 2012
a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Feb 04 2012
MATHEMATICA
LinearRecurrence[{2, -1}, {1476, 2934}, 50] (* Vincenzo Librandi, Feb 04 2012 *)
1458*Range[40]+18 (* Harvey P. Dale, Aug 17 2016 *)
PROG
(Magma) I:=[1476, 2934]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 04 2012
(PARI) for(n=1, 40, print1(1458n + 18", ")); \\ Vincenzo Librandi, Feb 04 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Mar 02 2009
STATUS
approved