

A025171


Reciprocal Chebyshev polynomial of second kind evaluated at 4 multiplied by (1)^n.


1



1, 2, 12, 56, 80, 1056, 832, 15232, 43776, 156160, 1012736, 473088, 17149952, 26730496, 220938240, 869564416, 1795883008, 17504796672, 6275465216, 267525816320, 635459076096, 3009494908928, 16186335035392, 15779248472064, 290539857510400
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OFFSET

0,2


LINKS

Robert Israel, Table of n, a(n) for n = 0..1660
Index entries for sequences related to Chebyshev polynomials.
Index entries for linear recurrences with constant coefficients, signature (2,16)


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


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

Sequence in context: A038175 A181541 A197230 * A127214 A304194 A124723
Adjacent sequences: A025168 A025169 A025170 * A025172 A025173 A025174


KEYWORD

sign


AUTHOR

Wouter Meeussen


STATUS

approved



