OFFSET
0,2
LINKS
FORMULA
G.f.: 1/(1+2x+16x^2).
a(n) = (-2)^n*Product_{k=1..n}(1 + 4*cos(k*Pi/(n+1))). - Peter Luschny, Nov 28 2019
a(n) = -2*a(n-1)-16*a(n-2). - Christian Krause, Dec 07 2023
MAPLE
seq(4^n*orthopoly[U](n, -1/4), n=0..40); # Robert Israel, Nov 21 2017
MATHEMATICA
Table[ a^n ChebyshevU[ n, -1/a ], {n, 0, 24} ]/.a->4
PROG
(PARI) a(n)=if(n<0, 0, polcoeff(1/(1+2*x+16*x^2)+x*O(x^n), n))
CROSSREFS
KEYWORD
sign,easy
AUTHOR
STATUS
approved