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A097740
Chebyshev U(n,x) polynomial evaluated at x=201.
4
1, 402, 161603, 64964004, 26115368005, 10498312974006, 4220295700182407, 1696548373160353608, 682008225714761968009, 274165610188961150786010, 110213893287736667854008011, 44305710936059951516160434412
OFFSET
0,2
COMMENTS
Used to form integer solutions of Pell equation a^2 - 101*b^2 =-1. See A097741 with A097742.
LINKS
R. Flórez, R. A. Higuita, A. Mukherjee, Alternating Sums in the Hosoya Polynomial Triangle, Article 14.9.5 Journal of Integer Sequences, Vol. 17 (2014).
Tanya Khovanova, Recursive Sequences
FORMULA
a(n) = 2*201*a(n-1) - a(n-2), n>=1, a(0)=1, a(-1):=0.
a(n) = S(n, 2*201)= U(n, 201), Chebyshev's polynomials of the second kind. See A049310.
G.f.: 1/(1-402*x+x^2).
a(n)= sum((-1)^k*binomial(n-k, k)*402^(n-2*k), k=0..floor(n/2)), n>=0.
a(n) = ((201+20*sqrt(101))^(n+1) - (201-20*sqrt(101))^(n+1))/(40*sqrt(101)), n>=0.
MATHEMATICA
LinearRecurrence[{402, -1}, {1, 402}, 12] (* Ray Chandler, Aug 11 2015 *)
CROSSREFS
Sequence in context: A158312 A237177 A128767 * A325151 A213605 A083815
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Aug 31 2004
STATUS
approved