OFFSET
1,2
COMMENTS
The corresponding values of x of this Pell equation are in A174748.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..200
Index entries for linear recurrences with constant coefficients, signature (46,-1).
FORMULA
a(n) = 46*a(n-1)-a(n-2) with a(1)=0, a(2)=4.
G.f.: 4*x^2/(1-46*x+x^2).
a(n) = 4*S(n-2,46), n>=1, with Chebyshev's S polynomials A049310 and S(-1,x)=0. - Wolfdieter Lang, Jun 19 2013
a(n) = (-4+23/sqrt(33))*(23+4*sqrt(33))^(-n)*(-1057-184*sqrt(33)+(23+4*sqrt(33))^(2*n))/2. - Colin Barker, Jun 10 2016
EXAMPLE
For n=3 a(3)=46*4-0=184; n=4, a(4)=46*184-4=8460.
MATHEMATICA
LinearRecurrence[{46, -1}, {0, 4}, 30]
PROG
(Magma) I:=[0, 4]; [n le 2 select I[n] else 46*Self(n-1)-Self(n-2): n in [1..20]];
(PARI) Vec(4*x^2/(1-46*x+x^2) + O(x^20)) \\ Colin Barker, Jun 10 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Apr 14 2010
STATUS
approved