OFFSET
0,2
COMMENTS
LINKS
FORMULA
a(n) = 2*243*a(n-1) - a(n-2), n>=1, a(0)=1, a(-1):=0.
a(n) = S(n, 2*243)= U(n, 243), Chebyshev's polynomials of the second kind. See A049310.
G.f.: 1/(1-486*x+x^2).
a(n)= sum((-1)^k*binomial(n-k, k)*486^(n-2*k), k=0..floor(n/2)), n>=0.
a(n) = ((243+22*sqrt(122))^(n+1) - (243-22*sqrt(122))^(n+1))/(44*sqrt(122)), n>=0.
MATHEMATICA
LinearRecurrence[{486, -1}, {1, 486}, 12] (* Ray Chandler, Aug 12 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Aug 31 2004
STATUS
approved