OFFSET
1,2
COMMENTS
The corresponding values of x of this Pell equation are in A176377.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..200
Index entries for linear recurrences with constant coefficients, signature (502,-1).
FORMULA
a(n) = 502*a(n-1)-a(n-2) with a(1)=0, a(2)=30.
G.f.: 30*x^2/(1-502*x+x^2).
a(n) = ((25+3r)^(2n-2)-(25-3r)^(2n-2))/(2r*5^(n-1)), where r=sqrt(70). - Bruno Berselli, Dec 14 2011
MATHEMATICA
LinearRecurrence[{502, -1}, {0, 30}, 20]
PROG
(Magma) I:=[0, 30]; [n le 2 select I[n] else 502*Self(n-1)-Self(n-2): n in [1..20]];
(Maxima) makelist(expand(((25+3*sqrt(70))^(2*n-2)-(25-3*sqrt(70))^(2*n-2))/(2*sqrt(70)*5^(n-1))), n, 1, 12); /* Bruno Berselli, Dec 14 2011 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Apr 16 2010
STATUS
approved